Temperature-dependent contactless electroreflectance and photoluminescence study of GaAlAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures

Temperature-dependent contactless electroreflectance (CER) and photoluminescence (PL) measurements in the range of 30 K < 300 K on two GaAlAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures with different well widths fabricated by molecular-beam epitaxy on (100) GaAs substrates are presented. For the CER measurement, the 11H transition is completely screened out by the two-dimensional electron gas and the prominent feature related to the Fermi energy edge singularity transition showed a Stokes shift to higher energy with respect to the 21H transition of the PL measurements at low temperature. From the Stokes shifts, the Fermi energy level of the system is evaluated, and hence, the density of the two-dimensional electron gas. The temperature-dependent PL measurements revealed two features, identified to be the 11H and 21H transitions. The relative intensities of the 11H and 21H transitions were analyzed taking into account the effect of the subband filling and the wave-function overlap factors. A good agreement is found between experimental data and theoretical calculation results. (C) 2001 American Institute of Physics.