Temperature-dependent integral exciton absorption in semiconducting GaAs crystals

This Letter is devoted to an experimental investigation of the temperature dependence of the fundamental absorption edge of thin GaAs layers grown by molecular beam epitaxy. Critical temperature $T_c$ = 135 K, above which the integral absorption becomes constant, corresponding values of critical damping parameter $\Gamma_c$ = 0.248 meV, and longitudinal-transverse splitting $\hbar\omega_{\mathrm{LT}}$ = 0.082 meV are determined experimentally. The temperature dependence of the true dissipative damping is separated.