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Journal Articles

2017

  • E. Farzana, Z. Zhang, P. K. Paul, A. R. Arehart, and S. A. Ringel, "Influence of metal choice on (010) β−Ga2O3 Schottky diode properties",  Appl. Phys. Lett. 110, 202102, May 2017 ( APL Editor's Pick)

  • S. Karki et al., “In Situ and Ex Situ Investigations of KF Postdeposition Treatment Effects on CIGS Solar Cells,” IEEE J. Photovolt., vol. 7, no. 2, pp. 665–669, March 2017.

  • C. M. Jackson, A. R. Arehart. T. J. Grassman, B. McSkimming, J. S. Speck, and S. A. Ringel, "Impact of Surface Treatment on Interface States of ALD Al2O3/GaN Interfaces", ECS Journal of Solid State Science and Technology 6 (8), P489-P494, June 2017.

2016

  • Z. Zhang, D. Cardwell, A. Sasikumar, E. C. H. Kyle, J. Chen, E. X. Zhang, D. M. Fleetwood, R. D. Schrimpf, J. S. Speck, A. R. Arehart and S. A. Ringel, "Correlation of proton irradiation induced threshold voltage shifts to deep level traps in AlGaN/GaN heterostructures", J. Appl. Phys. 119, 165704, 2016.

  • T. J. Grassman, D. J. Chmielewski, S. D. Carnevale, J. A. Carlin and S. A. Ringel, "GaAs0.75P0.25/Si Dual-Junction Solar Cells Grown by MBE and MOCVD", IEEE J. Photovolt., vol. 6(1), pp. 326-331, 2016. 

  • E. García-Tabarés, J. A. Carlin, T. J. Grassman, D. Martín, I. Rey-Stolle and S. A. Ringel, "Evolution of silicon bulk lifetime during III–V-on-Si multijunction solar cell epitaxial growth", Prog. Photovoltaics, DOI: 10.1002/pip.2703, 2016.

  • Z. Zhang, E. Farzana, A. R. Arehart, and S. A. Ringel, "Deep level defects throughout the bandgap of (010) b-Ga2O3 detected by optically and thermally stimulated defect spectroscopy", Appl. Phys. Lett., vol 108(5), pp. 052105, 2016.

  • X. Liu, C. M. Jackson, F. Wu, B. Mazumder, R. Yeluri, J. Kim, S. Keller, A. R. Arehart, S. A. Ringel, J. S. Speck, and U. K. Mishra, "Electrical and structural characterizations of crystallized Al2O3/GaN interfaces formed by in situ metalorganic chemical vapor deposition," J. Appl. Phys., vol 119, pp. 015303, JAN 7, 2016.

  • A. Sasikumar, A. R. Arehart, D. W. Cardwell, C. M. Jackson, W. Sun, Z. Zhang, S. A. Ringel, “Deep trap-induced dynamic on-resistance degradation in GaN-on-Si power MISHEMTs,” Microelectronics Reliability, vol. 56, pp. 37-44, JAN, 2016.

  • A.R. Arehart, A. Sasikumar, G.D. Via, B. Poling, E.R. Heller, S.A. Ringel, "Evidence for causality between GaN RF HEMT degradation and the Ec-0.57 eV trap in GaN," Microelectronics Reliability, vol. 56, pp.45-48, JAN, 2016.

  • X.S. Nguyen, X. L. Goh, L. Zhang, Z. Zhang, A. R. Arehart, S. A. Ringel, E. A. Fitzgerald, S. J. Chua, “Deep level traps in GaN LEDs grown by metal organic vapour phase epitaxy on an 8 inch Si(111) substrate,” Japanese Journal of Applied Physics, 55, 6, 2016. http://iopscience.iop.org/1347-4065/55/6/060306

  • J. Chen, Y. Puzyrev, E. Zhang, D. Fleetwood, R. Schrimpf, A. Arehart, S. Ringel, S. Kaun, E. Kyle, J. Speck, P. Saunier; C. Lee, S. Pantelides, “High-Field Stress, Low-Frequency Noise, and Long-term Reliability of AlGaN/GaN HEMTs,” IEEE Transactions on Device and Materials Reliability, PP, 99, 1-1, 2016. http://dx.doi.org/10.1109/TDMR.2016.2581178

  • J. I. Deitz, T. J. Grassman, and D. W. McComb, “Accessing High Spatial Resolution Low-Loss EELS Information without Cerenkov Radiation,” Microsc. Microanal., 22, S3, pp. 976–977, July 2016

  • J. I. Deitz, D. W. McComb, and T. J. Grassman, “Advancement of Heteroepitaxial III-V/Si Thin Films through Defect Characterization,” Microsc. Microanal., 22, S3, pp. 1538–1539, July 2016

  • J. I. Deitz, S. D. Carnevale, M. De Graef, D. W. McComb, and T. J. Grassman, “Characterization of encapsulated quantum dots via electron channeling contrast imaging,” Appl. Phys. Lett., 109, 6, p. 062101, Aug. 2016

  • E.  Gür, Fatih Akyol, Sriram Krishnamoorthy, Siddharth Rajan, Steven A. Ringel, “Deep level defects in N-rich and In-rich InxGa1−XN: in composition dependence,” Superlattices and Microstructures, http://dx.doi.org/10.1016/j.spmi.2016.05.009, May 2016

  • X.S. Nguyen, HW Hou, P De Mierry, P Vennéguès, F Tendille, AR Arehart, S. A. Ringel, E. A. Fitzgerald, S. J. Chua, “Deep level traps in semi‐polar n‐GaN grown on patterned sapphire substrate by metalorganic vapor phase epitaxy,” physica status solidi (b) 253 (11), 2225-2229, Aug. 2016

2015

  • Z. Zhang, E. Farzana, W. Y. Sun, J. Chen, E. Zhang, D. Fleetwood, R. Schrimpf, B. McSkimming, E. Kyle, J. Speck, A. Arehart, and S. Ringel, "Thermal Stability of Deep Level Defects Induced by High Energy Proton Irradiation in n-type GaN," J. Appl. Phys., vol 118, pp. 155701, OCT, 2015.

  • P. K. Paul, D. W. Cardwell, C. M. Jackson, K. Galiano, K. Aryal, J. P. Pelz, S. Marsillac, S. A. Ringel, T. J. Grassman, A. R. Arehart, "Direct nm-Scale Spatial Mapping of Traps in CIGS," IEEE Journal of Photovoltaics, vol. 5(5), pp. 1482, SEP, 2015.

  • J. I. Deitz, S. D. Carnevale, S. A. Ringel, D. W. McComb, T. J. Grassman, “Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization,” Journal of Visualized Experiments, vol. 101, pp. e52745, JUL 17, 2015.

  • I. Almansouri, S. Bremner, A. Ho-Baillie, H. Mehrvarz, X. Hao, G. Conibeer, T. J. Grassman, J. A. Carlin, A. Haas, S. A. Ringel and M. A. Green. "Designing Bottom Silicon Solar Cells for Multijunction Devices," IEEE J. Photovolt., vol. 5, pp. 683-690, MAR, 2015.

  • A. Sasikumar, A. R. Arehart, G. D. Via, B. Winningham, B. Poling, E. Heller,
    and S. A. Ringel, "Identification of an RF degradation mechanism in GaN based HEMTs triggered by midgap traps," Microelec. Reliability, vol. 55, pp. 2258-2262, 2015.

  • J. Chen, Y. S. Puzyrev, R. Jiang, E. X. Zhang, M. W. McCurdy, D. M. Fleetwood, R. D. Schrimpf, S. T. Pantelides, A. R. Arehart, S. A. Ringel, P. Saunier, and C. Lee, "Effects of Applied Bias and High Field Stress on the Radiation Response of GaN/AlGaN HEMTs," IEEE Transactions on Nuclear Science, Nuclear Science, vol. 62, pp. 2423-2430, 2015.

  • S. D. Carnevale, J. I. Deitz, J. A. Carlin, Y. N. Picard, D. W. McComb, M. De Graef, S. A. Ringel and T. J. Grassman. "Applications of Electron Channeling Contrast Imaging for the Rapid Characterization of Extended Defects in III-V/Si Heterostructures," IEEE J. Photovolt., vol. 5, pp. 676-682, MAR, 2015.

  • X. S. Nguyen, K. Lin, Z. Zhang, B. McSkimming, A. R. Arehart, J. S. Speck, S. A. Ringel, E. A. Fitzgerald and S. J. Chua. "Correlation of a generation-recombination center with a deep level trap in GaN," Appl. Phys. Lett., vol. 106, pp. 159903, APR 13, 2015.

  • Z. Zhang, A. R. Arehart, E. C. H. Kyle, J. Chen, E. X. Zhang, D. M. Fleetwood, R. D. Schrimpf, J. S. Speck and S. A. Ringel. "Proton irradiation effects on deep level states in Mg-doped p-type GaN grown by ammonia-based molecular beam epitaxy," Appl. Phys. Lett., vol. 106, pp. 022104, JAN 12, 2015.

  • J. I. Deitz, S. D. Carnevale, S. A. Ringel, D. W. McComb, and T. J. Grassman, “Extending characterization applications of electron channeling contrast imaging,” in 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC), pp. 1–4, 2015

  • E. W. Lee et al., “Layer-transferred MoS2/GaN PN diodes,” Appl. Phys. Lett., 107, 10, p. 103505, Sep. 2015.

2014

  • S. D. Carnevale, J. I. Deitz, J. A. Carlin, Y. N. Picard, M. De Graef, S. A. Ringel and T. J. Grassman. "Rapid misfit dislocation characterization in heteroepitaxial III-V/Si thin films by electron channeling contrast imaging," Appl. Phys. Lett., vol. 104, pp. 232111, JUN 9, 2014.

  • D. J. Chmielewski, T. J. Grassman, A. M. Carlin, J. A. Carlin, A. J. Speelman and S. A. Ringel. "Metamorphic GaAsP Tunnel Junctions for High-Efficiency III-V/IV Multijunction Solar Cell Technology," IEEE J. Photovolt., vol. 4, pp. 1301-1305, SEP, 2014.

  • T. J. Grassman, J. A. Carlin, B. Galiana, F. Yang, M. J. Mills and S. A. Ringel. "MOCVD-Grown GaP/Si Subcells for Integrated III-V/Si Multijunction Photovoltaics," IEEE J. Photovolt., vol. 4, pp. 972-980, MAY, 2014.

  • Z. Zhang, C. M. Jackson, A. R. Arehart, B. Mcskimming, J. S. Speck and S. A. Ringel. "Direct Determination of Energy Band Alignments of Ni/Al2O3/GaN MOS Structures Using Internal Photoemission Spectroscopy," J Electron Mater, vol. 43, pp. 828-832, APR, 2014.

2013

  • T. J. Grassman, C. Ratcliff, A. M. Carlin, J. A. Carlin, L. Yang, M. J. Mills and S. A. Ringel, "III-V/GaP Epitaxy on Si for Advanced Photovoltaics and Green Light Emitters," ECS Trans. vol. 50(9), pp. 321, 2013.

  • A. R. Arehart, A. Sasikumar, S. Rajan, G. D. Via, B. Poling, B. Winningham, E. R. Heller, D. Brown, Y. Pei, F. Recht, U. K. Mishra and S. A. Ringel. "Direct observation of 0.57 eV trap-related RF output power reduction in AlGaN/GaN high electron mobility transistors," Solid-State Electron., vol. 80, pp. 19-22, FEB, 2013.

  • D. W. Cardwell, A. Sasikumar, A. R. Arehart, S. W. Kaun, J. Lu, S. Keller, J. S. Speck, U. K. Mishra, S. A. Ringel and J. P. Pelz. "Spatially-resolved spectroscopic measurements of E-c-0.57 eV traps in AlGaN/GaN high electron mobility transistors," Appl. Phys. Lett., vol. 102, pp. 193509, MAY 13, 2013.

  • T. J. Grassman, J. A. Carlin, B. Galiana, L. -. Yang, F. Yang, M. J. Mills and S. A. Ringel. "Nucleation-related defect-free GaP/Si(100) heteroepitaxy via metal-organic chemical vapor deposition," Appl. Phys. Lett., vol. 102, pp. 142102, APR 8, 2013.

  • C. M. Jackson, A. R. Arehart, E. Cinkilic, B. McSkimming, J. S. Speck and S. A. Ringel. "Interface trap characterization of atomic layer deposition Al2O3/GaN metal-insulator-semiconductor capacitors using optically and thermally based deep level spectroscopies," J. Appl. Phys., vol. 113, pp. 204505, MAY 28, 2013.

  • R. D. Long, C. M. Jackson, J. Yang, A. Hazeghi, C. Hitzman, S. Majety, A. R. Arehart, Y. Nishi, T. P. Ma, S. A. Ringel and P. C. McIntyre. "Interface trap evaluation of Pd/Al2O3/GaN metal oxide semiconductor capacitors and the influence of near-interface hydrogen," Appl. Phys. Lett., vol. 103, pp. 201607, NOV 11, 2013.

  • A. Sasikumar, A. R. Arehart, S. Martin-Horcajo, M. F. Romero, Y. Pei, D. Brown, F. Recht, M. A. di Forte-Poisson, F. Calle, M. J. Tadjer, S. Keller, S. P. DenBaars, U. K. Mishra and S. A. Ringel. "Direct comparison of traps in InAlN/GaN and AlGaN/GaN high electron mobility transistors using constant drain current deep level transient spectroscopy," Appl. Phys. Lett., vol. 103, pp. 033509, JUL 15, 2013.

  • Z. Zhang, A. R. Arehart, E. Cinkilic, J. Chen, E. X. Zhang, D. M. Fleetwood, R. D. Schrimpf, B. McSkimming, J. S. Speck and S. A. Ringel. "Impact of proton irradiation on deep level states in n-GaN," Appl. Phys. Lett., vol. 103, pp. 042102, JUL 22, 2013.

2012

  • D. W. Cardwell, A. R. Arehart, C. Poblenz, Y. Pei, J. S. Speck, U. K. Mishra, S. A. Ringel and J. P. Pelz. "Nm-scale measurements of fast surface potential transients in an AlGaN/GaN high electron mobility transistor," Appl. Phys. Lett., vol. 100, pp. 193507, MAY 7, 2012.

  • E. Gur, G. Tabares, A. Arehart, J. M. Chauveau, A. Hierro and S. A. Ringel. "Deep levels in a-plane, high Mg-content MgxZn1-xO epitaxial layers grown by molecular beam epitaxy," J. Appl. Phys., vol. 112, pp. 123709, DEC 15, 2012.

  • A. Sasikumar, A. Arehart, S. Kolluri, M. H. Wong, S. Keller, S. P. DenBaars, J. S. Speck, U. K. Mishra and S. A. Ringel. "Access-Region Defect Spectroscopy of DC-Stressed N-Polar GaN MIS-HEMTs," IEEE Electron Device Lett., vol. 33, pp. 658-660, MAY, 2012.

  • Z. Zhang, C. A. Hurni, A. R. Arehart, J. S. Speck and S. A. Ringel. "Influence of V/III growth flux ratio on trap states in m-plane GaN grown by ammonia-based molecular beam epitaxy," Appl. Phys. Lett., vol. 101, pp. 152104, OCT 8, 2012.

  • Z. Zhang, C. A. Hurni, A. R. Arehart, J. Yang, R. C. Myers, J. S. Speck and S. A. Ringel. "Deep traps in nonpolar m-plane GaN grown by ammonia-based molecular beam epitaxy," Appl. Phys. Lett., vol. 100, pp. 052114, JAN 30, 2012.

2011

  • A. R. Arehart, A. A. Allerman and S. A. Ringel. "Electrical characterization of n-type Al0.30Ga0.70N Schottky diodes," J. Appl. Phys., vol. 109, pp. 114506, JUN 1, 2011.

  • A. R. Arehart, A. C. Malonis, C. Poblenz, Y. Pei, J. S. Speck, U. K. Mishra and S. A. Ringel. "Next generation defect characterization in nitride HEMTs," Physica Status Solidi C, vol. 8, 2011.

  • M. Gonzalez, A. M. Carlin, C. L. Dohrman, E. A. Fitzgerald and S. A. Ringel. "Determination of bandgap states in p-type In0.49Ga0.51P grown on SiGe/Si and GaAs by deep level optical spectroscopy and deep level transient spectroscopy," J. Appl. Phys., vol. 109, pp. 063709, MAR 15, 2011.

  • E. Gur, Z. Zhang, S. Krishnamoorthy, S. Rajan and S. A. Ringel. "Detailed characterization of deep level defects in InGaN Schottky diodes by optical and thermal deep level spectroscopies", Appl. Phys. Lett., vol. 99, pp. 229906, NOV 28, 2011.

  • D. N. Nath, E. Guer, S. A. Ringel and S. Rajan. "Growth model for plasma-assisted molecular beam epitaxy of N-polar and Ga-polar InxGa1-xN," J. Vac. Sci. Technol. B, vol. 29, pp. 021206, MAR, 2011.

  • C. Ratcliff, T. J. Grassman, J. A. Carlin and S. A. Ringel. "High temperature step-flow growth of gallium phosphide by molecular beam epitaxy and metalorganic chemical vapor deposition," Appl. Phys. Lett., vol. 99, pp. 141905, OCT 3, 2011.

  • K. Swaminathan, T. J. Grassman, L. -. Yang, Q. Gu, M. J. Mills and S. A. Ringel. "Optically-aligned visible/near-infrared dual-band photodetector materials and devices on GaAs using metamorphic epitaxy," J. Appl. Phys., vol. 110, pp. 063109, SEP 15, 2011.

  • K. Swaminathan, L. -. Yang, T. J. Grassman, G. Tabares, A. Guzman, A. Hierro, M. J. Mills and S. A. Ringel. "Metamorphic In0.20Ga0.80As p-i-n photodetectors grown on GaAs substrates for near infrared applications," Opt. Express, vol. 19, pp. 7280-7288, APR 11, 2011.

  • K. H. Tan, S. Wicaksono, W. K. Loke, D. Li, S. F. Yoon, E. A. Fitzgerald, S. A. Ringel and J. S. Harris Jr. "Molecular beam epitaxy grown GaNAsSb 1 eV photovoltaic cell," J. Cryst. Growth, vol. 335, pp. 66-69, NOV 15, 2011.

2010

  • A. R. Arehart, T. Homan, M. H. Wong, C. Poblenz, J. S. Speck and S. A. Ringel. "Impact of N- and Ga-face polarity on the incorporation of deep levels in n-type GaN grown by molecular beam epitaxy," Appl. Phys. Lett., vol. 96, pp. 242112, JUN 14, 2010.

  • A. R. Arehart, C. Poblenz, J. S. Speck and S. A. Ringel. "Effect of nitrogen plasma power on defect levels in Ni/n-GaN Schottky diodes grown by molecular beam epitaxy," J. Appl. Phys., vol. 107, pp. 054518, MAR 1, 2010.

  • T. J. Grassman, M. R. Brenner, M. Gonzalez, A. M. Carlin, R. R. Unocic, R. R. Dehoff, M. J. Mills and S. A. Ringel. "Characterization of Metamorphic GaAsP/Si Materials and Devices for Photovoltaic Applications," IEEE Trans. Electron Devices, vol. 57, pp. 3361-3369, DEC, 2010.

  • J. S. Lee, S. R. Bishop, T. J. Grassman and A. C. Kummel. "Plasma nitridation of Ge(100) surface studied by scanning tunneling microscopy," Surf. Sci., vol. 604, pp. 1239-1246, AUG 15, 2010.

  • D. N. Nath, E. Gur, S. A. Ringel and S. Rajan. "Molecular beam epitaxy of N-polar InGaN," Appl. Phys. Lett., vol. 97, pp. 071903, AUG 16, 2010.

  • J. H. Warner, C. D. Cress, S. R. Messenger, R. J. Walters, S. A. Ringel and J. Park. "A Deep Level Transient Spectroscopy Study of Electron and Proton Irradiated p(+) n GaAs Diodes," IEEE Trans. Nucl. Sci., vol. 57, pp. 1940-1945, AUG, 2010.

  • C. K. Yang, P. Roblin, F. De Groote, S. A. Ringel, S. Rajan, J. P. Teyssier, C. Poblenz, Y. Pei, J. Speck and U. K. Mishra. "Pulsed-IV Pulsed-RF Cold-FET Parasitic Extraction of Biased AlGaN/GaN HEMTs Using Large Signal Network Analyzer," IEEE Trans. Microwave Theory Tech., vol. 58, pp. 1077-1088, MAY, 2010.

2009

  • D. L. Feldwinn, J. B. Clemens, J. Shen, S. R. Bishop, T. J. Grassman, A. C. Kummel, R. Droopad and M. Passlack. "Anomalous hybridization in the In-rich InAs(001) reconstruction," Surf. Sci., vol. 603, pp. 3321-3328, NOV 15, 2009.

  • T. J. Grassman, S. R. Bishop and A. C. Kummel. "Density functional theory study of first-layer adsorption of ZrO2 and HfO2 on Ge(100)," Microelectron. Eng., vol. 86, pp. 249-258, MAR, 2009.

  • T. J. Grassman, M. R. Brenner, S. Rajagopalan, R. Unocic, R. Dehoff, M. Mills, H. Fraser and S. A. Ringel. "Control and elimination of nucleation-related defects in GaP/Si(001) heteroepitaxy," Appl. Phys. Lett., vol. 94, pp. 232106, JUN 8, 2009.

  • M. K. Hudait, M. Brenner and S. A. Ringel. "Metamorphic In0.7Al0.3As/In0.69Ga0.31As thermophotovoltaic devices grown on graded InAsyP1-y buffers by molecular beam epitaxy," Solid-State Electron., vol. 53, pp. 102-106, JAN, 2009.

  • M. K. Hudait, Y. Lin and S. A. Ringel. "Strain relaxation properties of InAsyP1-y metamorphic materials grown on InP substrates," J. Appl. Phys., vol. 105, pp. 061643, MAR 15, 2009.

  • N. L. Tran, S. R. Bishop, T. J. Grassman, G. C. Poon, F. I. Bohrer, W. C. Trogler and A. C. Kummel. "NO chemisorption dynamics on thick FePc and ttbu-FePc films," J. Chem. Phys., vol. 130, pp. 174305, MAY 7, 2009.

2008

  • A. R. Arehart, A. Corrion, C. Poblenz, J. S. Speck, U. K. Mishra, S. P. DenBaars and S. A. Ringel. "Comparison of deep level incorporation in ammonia and rf-plasma assisted molecular beam epitaxy n-GaN films," Physica Status Solidi C, vol. 5, pp. 1750-1752, 2008.

  • A. R. Arehart, A. Corrion, C. Poblenz, J. S. Speck, U. K. Mishra and S. A. Ringel. "Deep level optical and thermal spectroscopy of traps in n-GaN grown by ammonia molecular beam epitaxy," Appl. Phys. Lett., vol. 93, pp. 112101, SEP 15, 2008.

  • A. Armstrong, J. Caudill, A. Corrion, C. Poblenz, U. K. Mishra, J. S. Speck and S. A. Ringel. "Characterization of majority and minority carrier deep levels in p-type GaN : Mg grown by molecular beam epitaxy using deep level optical spectroscopy," J. Appl. Phys., vol. 103, pp. 063722, MAR 15, 2008.

  • T. J. Grassman, S. R. Bishop and A. C. Kummel. "An atomic view of Fermi level pinning of Ge(100) by O-2," Surf. Sci., vol. 602, pp. 2373-2381, JUL 15, 2008.

  • Y. Lin, A. R. Arehart, A. M. Carlin and S. A. Ringel. "Separation of bulk and surface electron transport in metamorphic InAs layers using quantitative mobility spectrum analysis," Appl. Phys. Lett., vol. 93, pp. 062109, AUG 11, 2008.

  • P. E. Smith, M. Lueck, S. A. Ringel and L. J. Brillson. "Atomic diffusion and interface electronic structure at In0.49Ga0.51P/GaAs heterojunctions," J. Vac. Sci. Technol. B, vol. 26, pp. 89-95, JAN, 2008.

2007

  • A. Armstrong, A. Corrion, C. Poblenz, U. K. Mishra, J. S. Speck and S. A. Ringel. "Comparison of deep level spectra in p-type and n-type GaN grown by molecular beam epitaxy", Phys. Status Solidi B-Basic Solid State Phys., vol. 244, pp. 4692-4692, DEC, 2007.

  • Y. Lin, J. A. Carlin, A. R. Arehart, A. M. Carlin and S. A. Ringel. "High-mobility two-dimensional electron gas in InAlAs/InAs heterostructures grown on virtual InAs substrates by molecular-beam epitaxy," Appl. Phys. Lett., vol. 90, pp. 012115, JAN 1, 2007.

  • D. Liu, M. Hudait, Y. Lin, H. Kim, S. A. Ringel and W. Lu. "Gate length scaling study of InAlAs/InGaAs/InAsP composite channel HEMTs," Solid-State Electron., vol. 51, pp. 838-841, JUN, 2007.

  • H. L. Mosbacker, S. El Hage, M. Gonzalez, S. A. Ringel, M. Hetzer, D. C. Look, G. Cantwell, J. Zhang, J. J. Song and L. J. Brillson. "Role of subsurface defects in metal-ZnO(0001) Schottky barrier formation," J. Vac. Sci. Technol. B, vol. 25, pp. 1405-1411, JUL-AUG, 2007.

  • P. E. Smith, M. Lueck, S. A. Ringel and L. J. Brillson. "Atomic diffusion and electronic structure in Al0.52In0.48P/GaAs heterostructures," J. Vac. Sci. Technol. B, vol. 25, pp. 1916-1921, NOV, 2007.

  • D. L. Winn, M. J. Hale, T. J. Grassman, A. C. Kummel, R. Droopad and M. Passlack. "Direct and indirect causes of Fermi level pinning at the SiO/GaAs interface," J. Chem. Phys., vol. 126, pp. 084703, FEB 28, 2007.

  • D. L. Winn, M. J. Hale, T. J. Grassman, J. Z. Sexton and A. C. Kummel. "Electronic properties of adsorbates on GaAs(001)-c(2x8)/(2x4)," J. Chem. Phys., vol. 127, pp. 134705, OCT 7, 2007.

2006

  • A. R. Arehart, B. Moran, J. S. Speck, U. K. Mishra, S. P. DenBaars and S. A. Ringel. "Effect of threading dislocation density on Ni/n-GaN Schottky diode I-V characteristics," J. Appl. Phys., vol. 100, pp. 023709, JUL 15, 2006.

  • A. Armstrong, A. Chakraborty, J. S. Speck, S. P. DenBaars, U. K. Mishra and S. A. Ringel. "Quantitative observation and discrimination of AlGaN- and GaN-related deep levels in AlGaN/GaN heterostructures using capacitance deep level optical spectroscopy," Appl. Phys. Lett., vol. 89, pp. 262116, DEC 25, 2006.

  • A. Armstrong, C. Poblenz, D. Green, U. Mishra, J. Speck and S. Ringel. "Impact of substrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN grown by molecular beam epitaxy," Appl. Phys. Lett., vol. 88, pp. 082114, FEB 20, 2006.

  • M. Gao, S. T. Bradley, Y. Cao, D. Jena, Y. Lin, S. A. Ringel, J. Hwang, W. J. Schaff and L. J. Brillson. "Compositional modulation and optical emission in AlGaN epitaxial films," J. Appl. Phys., vol. 100, pp. 103512, NOV 15, 2006.

  • M. Gonzalez, C. L. Andre, R. J. Walters, S. R. Messenger, J. H. Warner, J. R. Lorentzen, A. J. Pitera, E. A. Fitzgerald and S. A. Ringel. "Deep level defects in proton radiated GaAs grown on metamorphic SiGe/Si substrates," J. Appl. Phys., vol. 100, pp. 034503, AUG 1, 2006.

  • M. Gonzalez, C. L. Andre, R. J. Walters, S. R. Messenger, J. H. Warner, J. R. Lorentzen, A. J. Pitera, E. J. Fitzgerald and S. A. Ringel. "Deep level defects in proton radiated GaAs grown on metamorphic SiGe/Si substrates (vol 100, pg 034503, 2006)," J. Appl. Phys., vol. 100, pp. 119901, DEC 1, 2006.

  • M. K. Hudait, Y. Lin, P. M. Sinha, J. R. Lindemuth and S. A. Ringel. "Carrier compensation and scattering mechanisms in Si-doped InAsyP1-y layers grown on InP substrates using intermediate InAsyP1-y step-graded buffers," J. Appl. Phys., vol. 100, pp. 063705, SEP 15, 2006.

  • O. Kwon, J. J. Boeckl, M. L. Lee, A. J. Pitera, E. A. Fitzgerald and S. A. Ringel. "Monolithic integration of AlGaInP laser diodes on SiGe/Si substrates by molecular beam epitaxy," J. Appl. Phys., vol. 100, pp. 013103, JUL 1, 2006.

  • D. Liu, M. Hudait, Y. Lin, H. Kim, S. Ringel and W. Lu. "In0.53Ga0.47As/InAs0.3P0.7 composite channel high electron mobility transistors," Electron. Lett., vol. 42, pp. 307-309, MAR 2, 2006.

  • M. Lueck, C. Andre, A. Pitera, M. Lee, E. Fitzgerald and S. Ringel. "Dual junction GaInP/GaAs solar cells grown on metamorphic SiGe/Si substrates with high open circuit voltage," IEEE Electron Device Lett., vol. 27, pp. 142-144, MAR, 2006.

2005

  • C. Andre, J. Carlin, J. Boeckl, D. Wilt, M. Smith, A. Pitera, M. Lee, E. Fitzgerald and S. Ringel. "Investigations of high-performance GaAs solar cells grown on Ge-Si1-xGex-Si substrates," IEEE Trans. Electron Devices, vol. 52, pp. 1055-1060, JUN, 2005.

  • C. Andre, D. Wilt, A. Pitera, M. Lee, E. Fitzgerald and S. Ringel. "Impact of dislocation densities on n(+)/p and p(+)/n junction GaAs diodes and solar cells on SiGe virtual substrates," J. Appl. Phys., vol. 98, pp. 014502, JUL 1, 2005.

  • A. Armstrong, A. Arehart, D. Green, J. Speck, U. Mishra and S. Ringel. "A novel method to investigate defect states in MBE grown highly resistive GaN doped with C and Si," Physica Status Solidi C, vol. 2, pp. 2411-2414, 2005.

  • A. Armstrong, A. Arehart, D. Green, U. Mishra, J. Speck and S. Ringel. "Impact of deep levels on the electrical conductivity and luminescence of gallium nitride codoped with carbon and silicon," J. Appl. Phys., vol. 98, pp. 053704, SEP 1, 2005.

  • A. Armstrong, A. Arehart and S. Ringel. "A method to determine deep level profiles in highly compensated, wide band gap semiconductors," J. Appl. Phys., vol. 97, pp. 083529, APR 15, 2005.

  • M. Gao, Y. Lin, S. Bradley, S. Ringel, J. Hwang, W. Schaff and L. Brillson. "Spontaneous compositional superlattice and band-gap reduction in Si-doped AlxGa1-xN epilayers," Appl. Phys. Lett., vol. 87, pp. 191905, NOV 7, 2005.

  • M. Hale, D. Winn, T. Grassman, A. Kummel and R. Droopad. "Chemically resolved scanning tunneling microscopy imaging of Al on p-type Al0.1Ga0.9As(001)-c(2x8)/(2x4)," J. Chem. Phys., vol. 122, pp. 124702, MAR 22, 2005.

  • M. Hudait, Y. Lin, S. Goss, P. Smith, S. Bradley, L. Brillson, S. Johnston, R. Ahrenkiel and S. Ringel. "Evidence of interface-induced persistent photoconductivity in InP/In0.53Ga0.47As/InP double heterostructures grown by molecular-beam epitaxy," Appl. Phys. Lett., vol. 87, pp. 032106, JUL 18, 2005.

  • O. Kwon, J. Boeckl, M. Lee, A. Pitera, E. Fitzgerald and S. Ringel. "Growth and properties of AlGaInP resonant cavity light emitting diodes on Ge/SiGe/Si substrates," J. Appl. Phys., vol. 97, pp. 034504, FEB 1, 2005.

  • O. Kwon, Y. Lin, J. Boeckl and S. Ringel. "Growth and properties of digitally-alloyed AlGaInP by solid source molecular beam epitaxy," J Electron Mater, vol. 34, pp. 1301-1306, OCT, 2005.

  • Y. Lin, M. Hudait, S. Johnston, R. Ahrenkiel and S. Ringel. "Photoconductivity decay in metamorphic InAsP/InGaAs double heterostructures grown on InAsyP1-y compositionally step-graded buffers," Appl. Phys. Lett., vol. 86, pp. 071908, FEB 14, 2005.

  • P. Smith, S. Goss, M. Gao, M. Hudait, Y. Lin, S. Ringel and L. Brillson. "Atomic diffusion and band lineups at In0.53Ga0.47As-on-InP heterointerfaces," J. Vac. Sci. Technol. B, vol. 23, pp. 1832-1837, JUL-AUG, 2005.

  • C. Tivarus, J. Pelz, M. Hudait and S. Ringel. "Spatial resolution of ballistic electron emission microscopy measured on metal/quantum-well Schottky contacts," Appl. Phys. Lett., vol. 87, pp. 182105, OCT 31, 2005.

  • C. Tivarus, J. Pelz, M. Hudait and S. Ringel. "Direct measurement of quantum confinement effects at metal to quantum-well nanocontacts," Phys. Rev. Lett., vol. 94, pp. 206803, MAY 27, 2005.

2004

  • C. Andre, J. Boeckl, D. Wilt, A. Pitera, M. Lee, E. Fitzgerald, B. Keyes and S. Ringel. "Impact of dislocations on minority carrier electron and hole lifetimes in GaAs grown on metamorphic SiGe substrates," Appl. Phys. Lett., vol. 84, pp. 3447-3449, MAY 3, 2004.

  • A. Armstrong, A. Arehart, B. Moran, S. DenBaars, U. Mishra, J. Speck and S. Ringel. "Impact of carbon on trap states in n-type GaN grown by metalorganic chemical vapor deposition," Appl. Phys. Lett., vol. 84, pp. 374-376, JAN 19, 2004.

  • T. Grassman, G. Poon and A. Kummel. "Low coverage spontaneous etching and hyperthermal desorption of aluminum chlorides from Cl-2/Al(111)," J. Chem. Phys., vol. 121, pp. 9018-9030, NOV 8, 2004.

  • M. Hudait, Y. Lin, M. Palmisiano, C. Tivarus, J. Pelz and S. Ringel. "Comparison of mixed anion, InAsyP1-y and mixed cation, InxAl1-xAs metamorphic buffers grown by molecular beam epitaxy on (100)InP substrates," J. Appl. Phys., vol. 95, pp. 3952-3960, APR 15, 2004.

  • P. Smith, S. Goss, S. Bradley, M. Hudait, Y. Lin, S. Ringel and L. Brillson. "Atomic layer diffusion and electronic structure at In0.53Ga0.47As/InP interfaces," J. Vac. Sci. Technol. B, vol. 22, pp. 554-559, MAR-APR, 2004.

2003

  • C. Andre, J. Boeckl, C. Leitz, M. Currie, T. Langdo, E. Fitzgerald and S. Ringel. "Low-temperature GaAs films grown on Ge and Ge/SiGe/Si substrates," J. Appl. Phys., vol. 94, pp. 4980-4985, OCT 15, 2003.

  • M. Hudait, Y. Lin, M. Palmisiano and S. Ringel. "0.6-eV bandgap In0.69Ga0.31As thermophotovoltaic devices grown on InAsyP1-y step-graded buffers by molecular beam epitaxy," IEEE Electron Device Lett., vol. 24, pp. 538-540, SEP, 2003.

  • M. Hudait, Y. Lin, D. Wilt, J. Speck, C. Tivarus, E. Heller, J. Pelz and S. Ringel. "High-quality InAsyP1-y step-graded buffer by molecular-beam epitaxy," Appl. Phys. Lett., vol. 82, pp. 3212-3214, MAY 12, 2003.

  • M. Hudait, Y. Lin, D. Wilt, F. Wu, J. Speck, C. Tivarus, E. Heller, J. Pelz and S. Ringel. "High-quality InAsyP1-y step-graded buffer by molecular-beam epitaxy (vol 82, pg 3212, 2003)," Appl. Phys. Lett., vol. 83, pp. 587-587, JUL 21, 2003.

  • O. Kwon, M. Jazwiecki, R. Sacks and S. Ringel. "High-performance, metamorphic InxGa1-xAs tunnel diodes grown by molecular beam epitaxy," IEEE Electron Device Lett., vol. 24, pp. 613-615, OCT, 2003.

  • G. Poon, T. Grassman, J. Gumy and A. Kummel. "Direct and precursor-mediated hyperthermal abstractive chemisorption of Cl-2/Al(111)," J. Chem. Phys., vol. 119, pp. 9818-9828, NOV 8, 2003.

2002

  • A. Hierro, A. Arehart, B. Heying, M. Hansen, U. Mishra, S. DenBaars, J. Speck and S. Ringel. "Impact of Ga/N flux ratio on trap states in n-GaN grown by plasma-assisted molecular-beam epitaxy," Appl. Phys. Lett., vol. 80, pp. 805-807, FEB 4, 2002.

  • M. Hudait, C. Andre, O. Kwon, M. Palmisiano and S. Ringel. "High-performance In0.53Ga0.47 as thermophotovoltaic devices grown by solid source molecular beam epitaxy," IEEE Electron Device Lett., vol. 23, pp. 697-699, DEC, 2002.

  • R. Kaplar, S. Ringel, S. Kurtz, J. Klem and A. Allerman. "Deep-level defects in InGaAsN grown by molecular-beam epitaxy," Appl. Phys. Lett., vol. 80, pp. 4777-4779, JUN 24, 2002.

  • S. Ringel, J. Carlin, C. Andre, M. Hudait, M. Gonzalez, D. Wilt, E. Clark, P. Jenkins, D. Scheiman, A. Allerman, E. Fitzgerald and C. Leitz. "Single-junction InGaP/GaAs solar cells grown on Si substrates with SiGe buffer layers," Prog. Photovoltaics, vol. 10, pp. 417-426, SEP, 2002.

2001

  • J. Carlin, S. Ringel, A. Fitzgerald and M. Bulsara. "High-lifetime GaAs on Si using GeSi buffers and its potential for space photovoltaics," Solar Energy Mater. Solar Cells, vol. 66, pp. 621-630, FEB, 2001.

  • A. Hierro, A. Arehart, B. Heying, M. Hansen, J. Speck, U. Mishra, S. DenBaars and S. Ringel. "Capture kinetics of electron traps in MBE-grown n-GaN," Phys. Status Solidi B-Basic Res., vol. 228, pp. 309-313, NOV, 2001.

  • A. Hierro, M. Hansen, J. Boeckl, L. Zhao, J. Speck, U. Mishra, S. DenBaars and S. Ringel. "Carrier trapping and recombination at point defects and dislocations in MOCVD n-GaN," Phys. Status Solidi B-Basic Res., vol. 228, pp. 937-946, DEC, 2001.

  • R. Kaplar, A. Arehart, S. Ringel, A. Allerman, R. Sieg and S. Kurtz. "Deep levels and their impact on generation current in Sn-doped InGaAsN," J. Appl. Phys., vol. 90, pp. 3405-3408, OCT 1, 2001.

  • R. Kaplar, D. Kwon, S. Ringel, A. Allerman, S. Kurtz, E. Jones and R. Sieg. "Deep levels in p- and n-type InGaAsN for high-efficiency multi-junction III-V solar cells," Solar Energy Mater. Solar Cells, vol. 69, pp. 85-91, AUG, 2001.

2000

  • J.A. Carlin, S.A. Ringel, J.J. Boeckl, R.J. Kaplar and E.A. Fitzgerald, “High lifetime GaAs on Si using GeSi buffers and its potential for space applications,” Solar Energy Materials and Solar Cells, vol. 66, pp. 621-630, 2000.

  • J. Carlin, S. Ringel, E. Fitzgerald and M. Bulsara. "High quality GaAs growth by MBE on Si using GeSi buffers and prospects for space photovoltaics," Prog. Photovoltaics, vol. 8, pp. 323-332, MAY-JUN, 2000.

  • J. Carlin, S. Ringel, E. Fitzgerald, M. Bulsara and B. Keyes. "Impact of GaAs buffer thickness on electronic quality of GaAs grown on graded Ge/GeSi/Si substrates," Appl. Phys. Lett., vol. 76, pp. 1884-1886, APR 3, 2000.

  • T. Grassman, M. Knowles and A. Marcus. "Structure and dynamics of fluorescently labeled complex fluids by Fourier imaging correlation spectroscopy," Phys Rev E., vol. 62, pp. 8245-8257, DEC, 2000.

  • A. Hierro, D. Kwon, S. Ringel, M. Hansen, U. Mishra, S. DenBaars and J. Speck. "Deep levels in n-type Schottky and p(+)-n homojunction GaN diodes," MRS Internet J. Nitride Semicond. Res., vol. 5, pp. W11.80, 2000.

  • A. Hierro, D. Kwon, S. Ringel, M. Hansen, J. Speck, U. Mishra and S. DenBaars. "Optically and thermally detected deep levels in n-type Schottky and p(+)-n GaN diodes," Appl. Phys. Lett., vol. 76, pp. 3064-3066, MAY 22, 2000.

  • A. Hierro, D. Kwon, S. Ringel, S. Rubini, E. Pelucchi and A. Franciosi. "Photocapacitance study of bulk deep levels in ZnSe grown by molecular-beam epitaxy," J. Appl. Phys., vol. 87, pp. 730-738, JAN 15, 2000.

  • A. Hierro, S. Ringel, M. Hansen, J. Speck, U. Mishra and S. DenBaars. "Hydrogen passivation of deep levels in n-GaN," Appl. Phys. Lett., vol. 77, pp. 1499-1501, SEP 4, 2000.

  • M. Knowles, T. Grassman and A. Marcus. "Measurement of the dynamic structure function of fluorescently labeled complex fluids by Fourier imaging correlation spectroscopy," Phys. Rev. Lett., vol. 85, pp. 2837-2840, SEP 25, 2000.

1999

  • A. Hierro, D. Kwon, S. Goss, L. Brillson, S. Ringel, S. Rubini, E. Pelucchi and A. Franciosi. "Evidence for a dominant midgap trap in n-ZnSe grown by molecular beam epitaxy," Appl. Phys. Lett., vol. 75, pp. 832-834, AUG 9, 1999.

  • D. Kwon, R. Kaplar, S. Ringel, A. Allerman, S. Kurtz and E. Jones. "Deep levels in p-type InGaAsN lattice matched to GaAs," Appl. Phys. Lett., vol. 74, pp. 2830-2832, MAY 10, 1999.

  • S. Ringel and P. Grillot. "Electronic properties and deep levels in germanium-silicon," Germanium Silicon: Physics and Materials, vol. 56, pp. 293-346, 1999.

  • R. Sacks, L. Qin, M. Jazwiecki, S. Ringel, M. Clevenger, D. Wilt and M. Goorsky. "Growth and characterization of epitaxial FexAl1-x/(In,Al)As/InP and III-V/FexAl1-x/(In,Al)As/InP structures," J. Vac. Sci. Technol. B, vol. 17, pp. 1289-1293, MAY-JUN, 1999.

  • Q. Xu, J. Hsu, J. Carlin, R. Sieg, J. Boeckl and S. Ringel. "Topographic and electronic studies of wedge-shape surface defects on AlGaAs/GaAs films grown on Ge substrates," Appl. Phys. Lett., vol. 75, pp. 2111-2113, OCT 4, 1999.

1998

  • B. Anderson, L. Pelz, S. Ringel, B. Clymer and S. Collins. "Photonics laboratory with emphasis on technical diversity," IEEE Trans. Educ., vol. 41, pp. 194-202, AUG, 1998.

  • J. Carlin, S. Ringel, R. Sacks and K. Yap. "Role of Al content on surface structure evolution of low temperature AlxGa1-xAs and its effect an critical thickness," J. Vac. Sci. Technol. B, vol. 16, pp. 1372-1376, MAY-JUN, 1998.

  • S. Ringel and B. Chatterjee. "Electrical deactivation of interstitial Zn in heteroepitaxial InP by hydrogen and its effect on electronic properties," J. Appl. Phys., vol. 83, pp. 5904-5912, JUN 1, 1998.

  • R. Sieg, J. Carlin, J. Boeckl, S. Ringel, M. Currie, S. Ting, T. Langdo, G. Taraschi, E. Fitzgerald and B. Keyes. "High minority-carrier lifetimes in GaAs grown on low-defect-density Ge/GeSi/Si substrates," Appl. Phys. Lett., vol. 73, pp. 3111-3113, NOV 23, 1998.

  • R. Sieg, S. Ringel, S. Ting, E. Fitzgerald and R. Sacks. "Anti-phase domain-free growth of GaAs on offcut (001) Ge wafers by molecular beam epitaxy with suppressed Ge outdiffusion," J Electron Mater, vol. 27, pp. 900-907, JUL, 1998.

  • R. Sieg, S. Ringel, S. Ting, S. Samavedam, M. Currie, T. Langdo and E. Fitzgerald. "Toward device-quality GaAs growth by molecular beam epitaxy on offcut Ge/Si1-xGex/Si substrates," J. Vac. Sci. Technol. B, vol. 16, pp. 1471-1474, MAY-JUN, 1998.

  • S. Ting, E. Fitzgerald, R. Sieg and S. Ringel. "Range of defect morphologies on GaAs grown on offcut (001) Ge substrates," J Electron Mater, vol. 27, pp. 451-461, MAY, 1998.

  • Q. Xu, J. Hsu, S. Ting, E. Fitzgerald, R. Sieg and S. Ringel. "Scanning force microscopy studies of GaAs films grown on offcut Ge substrates," J Electron Mater, vol. 27, pp. 1010-1016, SEP, 1998.

1997

  • R. Hoffman, N. Fatemi, V. Weizer, P. Jenkins, M. Stan, S. Ringel, D. Scheiman, D. Wilt and D. Brinker. "High beginning-of-life efficiency p/n InP solar cells," Prog. Photovoltaics, vol. 5, pp. 415-422, NOV-DEC, 1997.

  • S. Ringel. "Hydrogen-extended defect interactions in heteroepitaxial InP materials and devices," Solid-State Electron., vol. 41, pp. 359-380, MAR, 1997.

  • S. Ringel, B. Chatterjee and R. Hoffman. "Hydrogen passivation of interstitial Zn defects in hetero-epitaxial InP cell structures and influence on device characteristics," Prog. Photovoltaics, vol. 5, pp. 423-431, NOV-DEC, 1997.

  • R. Sieg, R. Sacks and S. Ringel. "Application of pyrometric interferometry to the in situ monitoring of In0.52Al0.48As, In0.53Ga0.47As, and quaternary alloy growth on InP substrates," J. Cryst. Growth, vol. 175, pp. 256-261, MAY, 1997.

1996

  • B. Chatterjee and S. Ringel. "Effect of extended defects on the formation and dissociation kinetics of Zn-H complexes in heteroepitaxial p-type InP layers," Appl. Phys. Lett., vol. 69, pp. 839-841, AUG 5, 1996.

  • B. Chatterjee, S. Ringel and R. Hoffmann. "Hydrogen passivation of n(+)p and p(+)n heteroepitaxial InP solar cell structures," Prog. Photovoltaics, vol. 4, pp. 91-100, MAR-APR, 1996.

  • P. Grillot and S. Ringel. "Identification of compositionally invariant deep levels introduced by plastic strain in epitaxial Ge0.30Si0.70 and deformed bulk Si," Appl. Phys. Lett., vol. 69, pp. 2110-2112, SEP 30, 1996.

  • P. Grillot, S. Ringel and E. Fitzgerald. "Effect of composition on deep levels in heteroepitaxial GexS1-x layers and evidence for dominant intrinsic recombination-generation in relaxed Ge layers on Si," J Electron Mater, vol. 25, pp. 1028-1036, JUL, 1996.

  • P. Grillot, S. Ringel, J. Michel and E. Fitzgerald. "Structural, electronic, and luminescence investigation of strain-relaxation induced electrical conductivity type conversion in GeSi/Si heterostructures," J. Appl. Phys., vol. 80, pp. 2823-2832, SEP 1, 1996.

  • R. Sacks, R. Sieg and S. Ringel. "Investigation of the accuracy of pyrometric interferometry in determining AlxGa1-xAs growth rates and compositions," J. Vac. Sci. Technol. B, vol. 14, pp. 2157-2162, MAY-JUN, 1996.

  • R. Sieg and S. Ringel. "Reabsorption, band-gap narrowing, and the reconciliation of photoluminescence spectra with electrical measurements for epitaxial n-InP," J. Appl. Phys., vol. 80, pp. 448-458, JUL 1, 1996.

  • R. Sieg, R. Sacks, P. Grillot and S. Ringel. "Improved substrate temperature stability during molecular beam epitaxy growth using indium free mounting of small substrates of various shapes," J. Vac. Sci. Technol. A-Vac. Surf. Films, vol. 14, pp. 3283-3287, NOV-DEC, 1996.

1995

  • B. Chatterjee and S. A. Ringel. "Hydrogen Passivation and its Effects on Carrier Trapping by Dislocations in Inp/gaas Heterostructures," J. Appl. Phys., vol. 77, pp. 3885-3898, APR 15, 1995.

  • P. N. Grillot, S. A. Ringel, E. A. Fitzgerald, G. P. Watson and Y. H. Xie. "Electron Trapping Kinetics at Dislocations in Relaxed Ge0.3si0.7/si Heterostructures," J. Appl. Phys., vol. 77, pp. 3248-3256, APR 1, 1995.

  • P. N. Grillot, S. A. Ringel, E. A. Fitzgerald, G. P. Watson and Y. H. Xie. "Minority- and Majority-Carrier Trapping in Strain-Relaxed Ge0.3si0.7/si Heterostructure Diodes Grown by Rapid Thermal Chemical-Vapor-Deposition," J. Appl. Phys., vol. 77, pp. 676-685, JAN 15, 1995.

  • R. A. Mena, S. E. Schacham, E. J. Haugland, S. A. Alterovitz, S. B. Bibyk and S. A. Ringel. "Subband Quantum Scattering Times for AlGaAs/GaAs obtained using Digital Filtering," J. Appl. Phys., vol. 78, pp. 3940-3944, SEP 15, 1995.

  • R. A. Mena, S. E. Schacham, E. J. Haugland, S. A. Alterovitz, P. G. Young, S. B. Bibyk and S. A. Ringel. "Characterization of the Transport-Properties of Channel Delta-Doped Structures by Light-Modulated Shubnikov-De Haas Measurements," J. Appl. Phys., vol. 78, pp. 6626-6632, DEC 1, 1995.

  • R. M. Sieg, B. Chatterjee and S. A. Ringel. "Evidence for Enhanced Zinc Interstitial Concentration in Strain-Relaxed Heteroepitaxial Indium-Phosphide," Appl. Phys. Lett., vol. 66, pp. 3108-3110, JUN 5, 1995.

1994

  • B. Chatterjee, S. A. Ringel, R. Sieg, R. Hoffman and I. Weinberg. "Hydrogen Passivation of Dislocations in Inp on Gaas Heterostructures," Appl. Phys. Lett., vol. 65, pp. 58-60, JUL 4, 1994.

1991

  • S. A. Ringel and A. Rohatgi. "The Effects of Trap-Induced Lifetime Variations on the Design and Performance of High-Efficiency GaAs Solar-Cells," IEEE Trans. Electron Devices, vol. 38, pp. 2402-2409, NOV, 1991.

  • S. A. Ringel, A. W. Smith, M. H. MacDougal and A. Rohatgi. "The Effects of Cdcl2 on the Electronic-Properties of Molecular-Beam Epitaxially Grown Cdte/cds Heterojunction Solar-Cells," J. Appl. Phys., vol. 70, pp. 881-889, JUL 15, 1991.

  • A. Rohatgi, R. Sudharsanan, S. A. Ringel and M. H. MacDougal. "Growth and Process Optimization of Cdte and Cdznte Polycrystalline Films for High-Efficiency Solar-Cells," Solar Cells, vol. 30, pp. 109-122, MAY, 1991.

1990

  • S. A. Ringel, R. Sudharsanan, A. Rohatgi and W. B. Carter. "A Study of Polycrystalline Cd(zn, Mn)te/cds Films and Interfaces," J Electron Mater, vol. 19, pp. 259-263, MAR, 1990.

  • S. A. Ringel, R. Sudharsanan, A. Rohatgi, M. S. Owens and H. P. Gillis. "Effects of Annealing and Surface Preparation on the Properties of Polycrystalline Cdznte Films Grown by Molecular-Beam Epitaxy," J. Vac. Sci. Technol. A-Vac. Surf. Films, vol. 8, pp. 2012-2019, MAY-JUN, 1990.

1989

  • S. A. Ringel, A. Rohatgi and S. P. Tobin. "An Approach Toward 25-Percent Efficient Gaas Heteroface Solar-Cells," IEEE Trans. Electron Devices, vol. 36, pp. 1230-1237, JUL, 1989.

  • A. Rohatgi, S. A. Ringel, R. Sudharsanan, P. V. Meyers, C. H. Liu and V. Ramanathan. "Investigation of Polycrystalline Cdznte, Cdmnte, and Cdte-Films for Photovoltaic Applications," Solar Cells, vol. 27, pp. 219-230, OCT-DEC, 1989.

1988

  • A. B. Dewald, R. L. Frost, S. A. Ringel, J. P. Schaffer, A. Rohatgi, B. Nielsen and K. G. Lynn. "Positron-Annihilation Spectroscopy of Algaas/gaas Interfaces in Metalorganic Chemical Vapor-Deposition Grown Gaas Heterojunction Solar-Cells," J. Vac. Sci. Technol. A-Vac. Surf. Films, vol. 6, pp. 2248-2252, JUL-AUG, 1988.

  • A. Rohatgi, S. A. Ringel, J. Welch, E. Meeks, K. Pollard, A. Erbil, C. J. Summers, P. V. Meyers and C. H. Liu. "Growth and Characterization of Cdmnte and Cdznte Polycrystalline Thin-Films for Solar-Cells," Solar Cells, vol. 24, pp. 185-194, MAY-JUN, 1988.

1987

  • S. A. Ringel and S. Ashok. "Silicon Surface-Barrier Modification by Low-Energy Nitrogen Ion-Implantation," J. Electrochem. Soc., vol. 134, pp. 1494-1499, JUN, 1987.

1986

  • S. Ashok and S. A. Ringel. "Low-Energy Hydrogen Implantation for Silicon Schottky-Barrier Modification," Vacuum, vol. 36, pp. 917-920, NOV-DEC, 1986.

  • K. Giewont, S. A. Ringel and S. Ashok. "Synergistic Effects in Ion-Bombardment Modification of Silicon Schottky Contacts," J. Vac. Sci. Technol. A-Vac. Surf. Films, vol. 4, pp. 845-846, MAY-JUN, 1986.

  • S. A. Ringel, H. C. Chien and S. Ashok. "Evidence for the Formation of Polycrystalline Silicon by Argon Implantation and its Passivation by Atomic-Hydrogen," Appl. Phys. Lett., vol. 49, pp. 728-730, SEP 22, 1986.

  • S. A. Ringel, X. C. Mu, S. J. Fonash and S. Ashok. "A Study of Target Heating in Low-Energy Ion-Beam Processing," J. Vac. Sci. Technol. A-Vac. Surf. Films, vol. 4, pp. 2385-2388, SEP-OCT, 1986.