LATTICE-PARAMETER VARIATION IN DOPED GAAS SUBSTRATES DETERMINED USINGHIGH-RESOLUTION PHOTOLUMINESCENCE SPECTROSCOPY

Variations in the lattice parameters of commercially available undoped and Si-doped GaAs substrates have been studied using high resolution photoluminescence (PL) spectroscopy. The lattice parameter difference between high quality epitaxial layers of GaAs and the doped substrates upon which they are grown induces a biaxial strain in the epitaxial l ayer which can be detected with remarkable sensitivity using low tempe rature PL. The PL results show that a lattice mismatch as low as 0.001 3% can cause significant and well-resolved changes in the features of donor (D degrees X) and acceptor (A degrees X) bound exciton spectra, which are consistent with results obtained from samples subjected to e xternally applied biaxial stress. In addition to studying a variety of low lattice mismatch GaAs/GaAs:Si heterostructures, the technique is also successfully employed in the case of more highly strained GaAs gr own on an In0.004Ga0.996As substrate. (C) 1998 American Institute of P hysics. [S0021-8979(98)04223-6].