Optical transition in infrared photodetector based on V-groove Al0.5Ga0.5As/GaAs multiple quantum wire

Photoconductors based on V-grooved Al0.5Ga0.5As/GaAs multiple quantum wires (QWR) were fabricated. The geometric structure of the QWR was carefully ch aracterized by transmission electron microscopy and spatially resolved micr ophotoluminescence measurements. Infrared response at 9.2 mum is observed f rom the photocurrent spectrum measured at 80 K. It is attributed as the int ersubband transition in the quantum wire region. Due to the effective quant um confinement from the two (111)-surfaces forming the V groove, the overla pping between the ground state in the QWR and the one in the vertical quant um well is very small. This explains the weak photocurrent signal from the QWR photodetector. Theoretical design for a better wave function overlappin g and optical coupling is outlined from the analysis of two-dimensional spa tial distributions of the wave functions. (C) 2001 American Institute of Ph ysics.