Studies of lattice-matched InGaAs InAlAs single quantum well by photoreflectance spectroscopy and wet chemical etching

Photoreflectance (PR) spectra were measured from lattice-matched In0.53Ca0. 47As/In0.52Al0.48As Single quantum well structures (SQWs). The measurements allowed the observation of interband transitions from the heavy- and light -hole valence subbands to the conduction sub-bands. The transition energies measured from the PR spectra agree with those theoretically calculated fro m the confined levels in the SQW, A built-in electric field in the sample w as analyzed and located by sequential etching, measuring the series of PR s pectra after each etching step. A blue shift in the extrema of the Franz-Ke ldysh oscillations of the PR spectra, caused by the phase shift of the PR s pectra, was associated with each etching step. The phase spectra obtained f rom the PR spectra by Kramers-Kronig transformation was analyzed in terms o f the two-ray model. This analysis was used to calculate the etching depth in each etching step, and thus led to the etching rate. The etching rate ob tained from the phase shift analysis agrees with that measured by the atomi c force microscopy. (C) 1999 Elsevier Science Ltd. All rights reserved.