In-Plane Photocurrent Spectroscopy of Undoped GaAs/AlAs Quantum Well Heterostructures

Abstract
Photocurrent conducting parallel to the undoped GaAs/AlAs quantum well layers increases due to the increased number of photogenerated carriers by excitonic resonance absorption. This offers a simple and sensitive means to measure excitonic absorption spectral features without substrate removal and allows us to observe a sharp resonance absorption peak with a 15 meV linewidth at room temperature for the lowest heavy-hole free-excitonic transition in a 7.0 nm-wide GaAs single quantum well. Heavy-hole free-excitonic transitions associated with up to third-order quantized states are also observed.