• PDF / 436,938 Bytes
• 5 Pages / 414.72 x 648 pts Page_size
• 54 Downloads / 227 Views

DOWNLOAD

REPORT

---

Mg-GaN, GaN/AIGaN SCH structures, and GaN on ZnO Substrates

H. Morkoq*, W. Kim, 0. Aktas, A. Salvador, and A. Botchkarev, University of Illinois, Coordinated Science Laboratory and Materials Research Laboratory, 104 South Goodwin Avenue, Urbana, IL 61801 D. C. Reynolds, and D. C. Look, University Research Center, Wright State University, Dayton Ohio 45435 M. Smith, G. D. Chen, J. Y. Lin, and H. X. Jiang, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601 T.J. Schmidt, X.H. Yang, W. Shan, and J.J. Song, Dept. of Physics, Oklahoma State University, Stillwater, OK 74078-0444 B. Goldenberg, Honeywell Technology Center, 4B75, 1201 State Highway 55 Plymouth MN 55441-4799 C. W. Litton and K. Evans, Electronic Research Directorate,WL/ELR, Building 620 Wright Patterson AFB, OH 45433 Abstract GaN films and GaN/AlGaN heterostructures have been gro wn by MBE. GaN films doped with varying levels of Mg indicate effective mass acceptor at low doping concentrations, as determined from strong photoluminescence emission at about 380 nm. As the Mg concentration is increased the photoluminescence emission line red shifts considerably, indicating the formation of Mg-related or induced complexes whose lifetimes are relatively short. GaN/AlGaN separate confinement heterostructures grown on sapphire show strong near ultraviolet stimulated emission at room temperature in a side-pumping configuration. The pumping threshold for stimulated emission at room temperature was found to be -90 kW/cm 2 . Initial GaN films grown on ZnO substrates show the A exciton in low temperature photoluminescence. ZnO is being considered for nitride growth because of its stacking order and close lattice match. * On sabbatical leave at Wright Laboratory on a University Resident Research Program funded by AFOSR. Introduction Unlike Si and GaAs technologies, devices based on group-III nitrides are capable of operating at high temperatures and hostile environments as well as emitters and detectors for wavelengths shorter than greenl,2, 3 ,4 . Most notable of the group-III nitrides are AIN, GaN, InN and their alloys, which are all wide bandgap semiconductors. They crystallize in both wurtzite and zincblende polytypes, the former being the more stable phase. Wurtzitic GaN, AIN and InN have direct room temperature bandgaps of 3.4, 6.2, and 1.9 eV, respectively. The group-Ill nitrides thus formed span a continuous range of direct bandgap energies throughout much of the visible spectrum well into the ultraviolet wavelengths. This is one of the reasons fueling the recent interest in GaN, AIN, InN, and their tertiary alloys for short wavelength optoelectronic device applications. These optoelectronic devices, especially emitters such as the light emitting diodes5 (LEDs) and lasers, can be active in the yellow, green, blue, and ultraviolet (uv) wavelengths. LEDs have expanded remarkably not only in terms of the range of wavelengths of emissiun available, but also brightness 6 ,7-8. These LEDs have proved to be reliable and have applications, for e