Suppression of bandgap shifts in GaAs/AlGaAs quantum wells using strontium fluoride caps

Abstract

Quantum well intermixing using dielectric caps has been studied using photoluminescence at 77 K. The structures which have been investigated, including shallow depth single quantum wells and multiquantum well waveguiding material, are highly sensitive to the presence of surface defects during annealing. Samples capped with either silicon nitride or silica have shown considerable energy shifts after processing in a rapid thermal annealer, and large energy shifts have also been found in uncapped material. Samples capped with strontium fluoride have shown negligible intermixing of the quantum wells.