DEUTERIUM IN INGAAS/GAAS STRAINED QUANTUM-WELLS - AN OPTICALLY-ACTIVE IMPURITY

Low-temperature photoluminescence in InGaAs/GaAs strained quantum wells shows the appearance, upon deuterium irradiation, of two bands at energies below the heavy-hole free exciton. The deeper band is due to recombination at a deuterium impurity (or at a deuterium-defect complex), while the shallower band is attributed to an exciton bound to the deuterium-related state. The binding energies of these two bands depend on alloy composition and well width and show a maximum for finite well width values as expected by theoretical calculations. The absence of these bands in samples irradiated with helium shows that the two bands are related to deuterium atoms in the samples rather than to recombination centres due to the irradiation procedure. Thermal annealing treatments indicate that the dissociation energy of the deuterium-related radiative state is comparable to that measured in GaAs for complexes formed by deuterium and deep traps.