Optical properties of undoped n-AlGaN/GaN superlattices as affected by built-in and external-electric field and by ar-implantation-induced partial disordering

• Published in: Journal of electronic materials Vol. 31; no. 5; pp. 384 - 390
• Main Authors: Polyakov, A. Y., Smirnov, N. B., Govorkov, A. V., Shlensky, A. A., Mil’vidskii, M. G., Pearton, S. J., Faleev, N. N., Bublik, V. T., Chsherbatchev, K. D., Osinsky, A., Norris, P. E., Dravin, V. A., Wilson, R. G.
• Format: Journal Article
• Language: English
• Published: 01.05.2002
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-002-0088-5

High-resolution x-ray diffraction patterns and 90 K microcathodoluminescence (MCL) spectra were taken for undoped, symmetric AlGaN/GaN superlattices (SLs) with GaN quantum-well (QW) widths of 35 A and 80 A. The shortperiod SL spectra were blue shifted by about 60 meV compared to the GaN substrate, and the magnitude of the blue shift was increased by about 20 meV by application of a reverse bias of -3 V (electric field of about 4 times 10 super(5) V/cm) to a Schottky diode prepared on this SL. A small red shift of about 40 meV compared to GaN was observed for the long-period SL. The two latter observations were interpreted as manifestations of the presence of a strong built-in piezo-electric field, giving rise to the quantum-confined Stark effect (QCSE). Partial disordering of the short-period SL was observed after Ar ion implantation (energy 150 keV, dose 8 times 10 super(13) cm super(-2) and 80 keV, 2 times 10 super(13) cm super(-2)) and subsequent annealing at 1000 degree C for 3 h under the protective layer of Si sub(3)N sub(4). However, it was observed that this partial disordering was accompanied by strain relaxation via formation of misfit dislocations or cracks.