Observation of Γ-X resonances in type-I GaAs/AlAs semiconductor superlattices: Anomaly in photoluminescence

Abstract

We report the direct observation of \ensuremath{\Gamma}-X resonances in type-I GaAs/AlAs semiconductor superlattices under an electric field. Photoluminescence (PL) associated with the first ${\mathrm{X}}_{\mathrm{z}}$ state in the AlAs and the first \ensuremath{\Gamma} heavy-hole state in the GaAs was found in type-I superlattices. The PL strongly increased its intensity due to \ensuremath{\Gamma}-X mixing, by tuning the resonance between the ${\mathrm{X}}_{\mathrm{z}}$ state and the second \ensuremath{\Gamma}-electron state in the adjacent GaAs layer. This observation gives clear evidence that \ensuremath{\Gamma}-X scattering and mixing often occur even in type-I superlattices under an electric field.