Bloch wave conditions for continuum states in the InGaAs/GaAs QWIPs

Abstract

We study the optical transition between bound-to-(quasi)-continuum states in InGaAs/GaAs quantum well infrared photodetectors (QWIPs) by investigating the boundary conditions of the extended states. Comparing running wave function and Bloch wave function with experimental results, it is find out that Bloch wave function is the much more suitable boundary condition for InGaAs/GaAs QWIPs with multiple quantum well (QW) structure. The blueshift of the responding peak is smaller when the Bloch wave boundary conditions apply. By changing the width of the InGaAs QW, we observe the changing of characterizing photocurrent peak corresponding to two boundary conditions respectively. The blueshift of the responding peak is smaller when Bloch wave boundary conditions apply. The detailed dependence of peak response wavelength and device operation mode on the indium mole fraction and InGaAs QW width is also investigated, offering guidance for device designing and optimization.