Appropriate analytical description of the temperature dependence of exciton peak positions in GaAs/AlxGa1−xAs multiple quantum wells and the Γ8v−Γ6c gap of GaAs

We have performed a detailed numerical reinvestigation of the photoluminescence peak position data given by G. Oelgart et al. [J. Appl. Phys. 74, 2742 (1993)] for the ground state heavy-and light-hole excitons in a high quality molecular beam epitaxially grown GaAs/Al0.3Ga0.7As multiple quantum well structure. Appropriate fittings of the measured temperature dependencies of exciton peak positions from 4.2 up to 340 K are shown to be provided by a novel analytical four-parameter representation developed recently by one of the authors for the gap shrinkage effect in semiconductors. The magnitude of the limiting (T→∞) shrinkage coefficient, α=0.475 meV/K, and the associated average phonon temperature, Θ=222.4 K, have been determined. Characteristic qualitative differences and basic deficiencies of earlier three-parameter models are discussed and illustrated numerically by comparisons with various experimental observations from low to high temperatures.