Award Abstract # 1210282
Materials World Network: Investigation of Nonpolar and Semipolar GaN on Si and Sapphire: Optical Processes and Efficiency

NSF Org: DMR
Division Of Materials Research
Recipient: VIRGINIA COMMONWEALTH UNIVERSITY
Initial Amendment Date: August 29, 2012
Latest Amendment Date: August 29, 2012
Award Number: 1210282
Award Instrument: Standard Grant
Program Manager: Miriam Deutsch
mdeutsch@nsf.gov
 (703)292-5360
DMR
 Division Of Materials Research
MPS
 Directorate for Mathematical and Physical Sciences
Start Date: September 1, 2012
End Date: August 31, 2016 (Estimated)
Total Intended Award Amount: $300,000.00
Total Awarded Amount to Date: $300,000.00
Funds Obligated to Date: FY 2012 = $300,000.00
History of Investigator:
  • Hadis Morkoc (Principal Investigator)
    hmorkoc@vcu.edu
  • Umit Ozgur (Co-Principal Investigator)
  • Vitaliy Avrutin (Co-Principal Investigator)
Recipient Sponsored Research Office: Virginia Commonwealth University
910 WEST FRANKLIN ST
RICHMOND
VA  US  23284-9005
(804)828-6772
Sponsor Congressional District: 04
Primary Place of Performance: Virginia Commonwealth University
Richmond
VA  US  23298-0568
Primary Place of Performance
Congressional District:
04
Unique Entity Identifier (UEI): MLQFL4JSSAA9
Parent UEI: WXQLZ1PA6XP3
NSF Program(s): ELECTRONIC/PHOTONIC MATERIALS,
XC-Crosscutting Activities Pro
Primary Program Source: 01001213DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 7488, 9161, AMPP
Program Element Code(s): 177500, 722200
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.049

ABSTRACT

TECHNICAL SUMMARY:
The objective of this Materials World Network project is to investigate the fundamentals of nonpolar and semipolar GaN growth on low cost Si and sapphire substrates with the aim of understanding the mechanisms governing defect formation and constituent/impurity incorporation as well as processes responsible for radiative recombination. Insight into mechanisms responsible for the defect formation will make it possible to devise approaches for reducing the defect density, particularly the stacking faults and partial dislocations, and produce high-optical-quality material for light-emitting diodes with enhanced brightness and potentially for laser diodes. The absence of polarization in nonpolar GaN and substantially reduced polarization in semipolar GaN will allow higher recombination efficiencies and eliminate the dependence of emission energy on injection level. After interrogating cleanly the optical matrix elements, In and Mg incorporation, and Mg activation energy in optimized GaN films, systematic studies of oscillator strengths and radiative recombination rates in nonpolar and semipolar InGaN/GaN and GaN/AlGaN quantum wells and double heterostructures will be undertaken to answer the critical question which non-polar and semipolar GaN orientation has the potential to provide higher efficiency light emitters than polar c-plane GaN.

NON-TECHNICAL SUMMARY:
A multi-institutional/multidisciplinary international program bringing together the unique expertise in growth, available at the Virginia Commonwealth University, extensive capabilities of precise optical measurements at the University of Magdeburg (Germany), and demonstrated experience in theoretical modeling at the University of Montpellier 2 (France) will be undertaken in an effort to understand the synthesis and properties of transformative nonpolar and semipolar nitride semiconductor structures for high efficiency light emitters. This approach will shed the much needed light into the fundamentals of defect formation, impurity incorporation, and optical processes and thus will lay the critical groundwork for attainment of bright light sources for solid-state lighting, as well as lasers and detectors for consumer and military applications. This Materials World Network project will allow a broad perspective of materials science, engineering, and semiconductor theory and provide a fertile ground for teaching graduate and undergraduate students the intricacies of science and soft skills necessary for success in the global, cyber-enabled nanotechnology workforce, with the additional benefit of exposure to cultures of science in the US, Germany, and France. Cross training of graduate students by leading international groups, research experiences for undergraduate students, and expansion of outreach programs for middle school students in the fields of materials science and semiconductor devices will go a long way for training the future skilled workforce.

This project is supported by the Electronic and Photonic Materials program and Office of Special Programs, Division of Materials Research.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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(Showing: 1 - 10 of 16)
D. Rosales, B. Gil, M. Monavarian, F. Zhang, S. Okur, N. Izyumskaya, V. Avrutin, Ü. Özgür, and H. Morkoç "Temperature-dependent time-resolved photoluminescence measurements of (1-101)-oriented semi-polar AlGaN/GaN MQWs" Proceedings of SPIE , v.9363 , 2015 , p.93630J-1 10.1117/12.2076207
D.Rosales, B. Gil, T. Bretagnon, B. Guizal, N. Izyumskaya, M. Monavarian, F. Zhang, S. Okur, V. Avrutin, Ü. Özgür, and H. Morkoç "Recombination dynamics of excitons with low non-radiative component in semi-polar (10-11)-oriented GaN/AlGaN MQWs" Journal of Applied Physics , v.116 , 2014 , p.093517-1 10.1063/1.4894513
D. Rosales, B. Gil, T. Bretagnon, F. Zhang, S. Okur, M. Monavarian, N. Izyumskaya, V. Avrutin, Ü. Özgür, H. Morkoç, and J. H. Leach "Excitonic recombination dynamics in non-polar GaN/AlGaN quantum wells" Journal of Applied Physics , v.115 , 2014 , p.073510 10.1063/1.4865959
D. Rosales, B. Gil, T. Bretagnon, F. Zhang, S. Okur, M. Monavarian, N. Izyumskaya, V. Avrutin, Ü. Özgür, H. Morkoç, and J. H. Leach "Polarized time-resolved photoluminescence measurements of m-plane AlGaN/GaN MQWs" Proceedings of SPIE, The International Society of Optical Engineering. , v.8986 , 2014 , p.89860L doi: 10.1117/12.2036984
M. Monavarian, D. Rosales, B. Gil, N. Izyumskaya, S. Das, Ü. Özgür, H. Morkoç, and V. Avrutin "Exciton localization in (1122)-oriented semi-polar InGaN multiple quantum wells" Proceedings of SPIE , v.9748 , 2016 , p.974826-1 10.1117/12.2213835
M. Monavarian, N. Izyumskaya, M. Müller, S. Metzner, P. Veit, N. Can, S. Das, Ü. Özgür, F. Bertram, J. Christen, H. Morkoç, and V. Avrutin "Improvement of optical quality of semipolar (11-22) GaN on m-plane sapphire by in-situ epitaxial lateral overgrowth" Journal of Applied Physics , v.119 , 2016 , p.145303 10.1063/1.4945770
M. Monavarian, S. Hafiz, N. Izyumskaya, S. Das, Ü. Özgür, H. Morkoç, and V. Avrutin "Wurtzite/zinc-blende electronic-band alignment in basal-plane stacking faults in semi-polar GaN" Proceedings of SPIE , v.9748 , 2016 , p.974827-1 10.1117/12.2213859
M. Monavarian, S. Metzner, N. Izyumskaya, M. Muller, S. Okur, F. Zhang, N. Can, S. Das, V. Avrutin, Ü. Özgür, F. Bertram, J. Christen, and H. Morkoç "Enhancement of optical and structural quality of semipolar GaN by introducing nanoporous SiNx interlayers" Proceedings of SPIE , v.9363 , 2015 , p.93632I-1 10.1117/12.2079180
M. Monavarian, S. Metzner, N. Izyumskaya, S. Okur, F. Zhang, N. Can, S. Das, V. Avrutin, Ü. Özgür, F. Bertram, J. Christen, and H. Morkoç "Indium-incorporation efficiency of semipolar GaN as compared to polar c-plane in (11-22) InGaN-based light emitting diodes" Proceedings of SPIE , v.9363 , 2015 , p.93632P-1 10.1117/12.2080325
N. Izyumskaya, F. Zhang, S. Okur, T. Selden, V. Avrutin, Ü. Özgür, S. Metzner, C. Karbaum, F. Bertram, J. Christen, and H. Morkoç "Optical studies of strain and defect distribution in semipolar (1-101) GaN on patterned Si substrates" Journal of Applied Physics , v.114 , 2013 , p.N/A 10.1063/1.4821343
N. Izyumskaya, S. Okur, F. Zhang, M. Monavarian, V. Avrutin, Ü. Özgür, S. Metzner, C. Karbaum, F. Bertram, J. Christen, and H. Morkoç "Optical properties of m-plane GaN grown on patterned Si(112) substrates by MOCVD using a two-step approach" Proceedings of SPIE, The International Society of Optical Engineering. , v.3986 , 2014 , p.898629 doi:10.1117/12.2037930
(Showing: 1 - 10 of 16)

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

This multidisciplinary, multi-institutional research program was dedicated to the exploration of novel growth methods for achieving high optical efficiency III-nitride heterostructures of nonpolar and semipolar orientations on inexpensive Si and sapphire substrates. Although energy-saving GaN-based light emitting diodes have been remarkably successful in revolutionizing our lives, the mainstay for the technological development of LEDs has been the structures having (0001) polar orientation, which suffer from built-in polarization electric fields and limited solubility of indium. These drawbacks prevent further improvement of energy efficiency, particularly for devices operating in the green spectral range. Structures of nonpolar and semipolar GaN orientations address the aforementioned issues by eliminating polarization fields and enhancing indium incorporation, and therefore, hold great promise for the production of high efficiency LEDs, including devices emitting in green, with the added benefit of longer lifetimes and lower maintenance cost.

The aim of this program was to investigate mechanisms of defect formation, impurity incorporation, and radiative recombination in nonpolar and semipolar GaN, with the focus on (1) mechanisms of formation and propagation of extended defects to establish growth conditions leading to high-quality nonpolar and semipolar GaN on Si and sapphire; (2) incorporation of indium into nonpolar and semipolar GaN; (3) theoretical and experimental investigation of radiative recombination in nonpolar and semipolar GaN/AlGaN and InGaN/GaN heterostructures and quantum wells; and (4) creation of an educational environment for cross-disciplinary training of students in advanced growth methods, solid-state theory, and cutting-edge structural and optical characterization techniques, allowing concurrent observation of optical activity of defects and their distribution with nanoscale spatial resolution.

We established the growth of nonpolar m-plane and semipolar  GaN on patterned Si (112) and (100) substrates, respectively, and semipolar  GaN on planar m-plane sapphire. Our studies performed in collaboration with Otto-von-Guericke University of Magdeburg (Germany) on semipolar  GaN grown on patterned Si(001) revealed a new mechanism of threading-dislocation blocking by rows of stacking faults. Consequently, we achieved semiopolar material with low defect density and high optical quality, comparable to the state-of-the-art polar variety. This finding paves the way for semipolar active regions with reduced density of extended defects, which are imperative for high-efficiency light emitters.

 

Substantial improvement of optical quality of semipolar  GaN on m-sapphire substrates was achieved via optimization of epitaxial lateral overgrowth technique through in situ deposited silicon nitride nanoporous mask (nano-ELO). PL intensities and carrier decay times approaching those of the state-of-the-art polar reference samples were obtained. Semipolar  InGaN LEDs grown on nano-ELO GaN templates exhibited significantly enhanced (by 3-4 at %) indium incorporation as compared to polar structures. Combined with the improved optical quality of the material prepared by nano-ELO, this finding endorses semipolar  GaN as a promising candidate for light-emitting devices operating the green spectral range.

 

Comprehensive investigations of polarization of emitted light and temperature dependent recombination dynamics  in semipolar  and nonpolar GaN/AlGaN quantum wells were performed in collaboration with University of Montpellier 2 (France). These studies revealed higher optical quality of the semipolar structures with predominantly radiative recombination owing to relatively low density of extended defects, thermally stable population of free and localized excitons, and high degree of polarization (58%) of emanating light. These findings indicate that   GaN structures are also suitable for polarized light emitters. The high optical quality of these structures also made it possible to use the experimental data for developing theoretical models describing oscillator strengths of optical transitions in nonpolar and semipolar GaN.

Through collaboration with world leading experts in materials characterization (Otto-von-Guericke University of Magdeburg) and solid-state theory (University of Montpellier-2), this international research program provided an ideal multidisciplinary environment offering unique possibilities for cross-disciplinary training of graduate students. This training was further enhanced through the visits of PhD students from our partner institutions, S. Metzger and M. Mueller of Otto-von-Guericke University of Magdeburg and D. Rosales of University of Montpellier-2. Moreover, research outcomes of this program were incorporated into graduate courses on Semiconductor Optoelectronics and Characterization of Semiconductor Materials and Devices and undergraduate courses on Introduction to Optoelectronics and Photonics in Energy and Medicine. At VCU, 6 graduate students directly participated in this project and 4 PhD dissertations resulted during the course of this project. One additional dissertation work was performed at University of Montpellier, and one more at Otto-von-Guericke University of Magdeburg.

Finally, scientific findings of this effort have been widely disseminated through publications in peer-reviewed journals, and presentations at international conferences and workshops. To date, 16 peer-reviewed articles have been published, 1 manuscript is in press, 1 manuscript is under review, and 8 conference presentations and talks have been delivered.

 


Last Modified: 10/18/2016
Modified by: Vitaliy Avrutin

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