Electronic Raman scattering from intersubband transitions in GaN/AlGaN quantum wells

We present a Raman scattering study of two GaN/AlxGa1-xN multiple quantum well (MQW) structures with x = 0.3 and x = 0.4 and well widths of 6 nm and 4 nm respectively, they were nominally undoped but are expected to contain a low-density, n-type, carrier population due to the residual donors in the barriers. Polarization dependent Raman scattering was performed at room temperature, strong scattering due to intersubband transitions (ISBT's) in the GaN quantum wells was observed from both the e(1)-e(2) and e(1)-e(3) transitions for both samples. The first sample has an e(1)-e(2) transition at 300 meV and e(1)-e(3) at 480 meV whilst the second sample has an e(1)-e(2) transition at 360 meV and e(1)-e(3) at 580 meV. The full width half maximum of the Raman peaks is lower than that reported in infra-red absorption for similar, heavily doped, MQW structures. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.