MBE AND MOCVD GROWTH OF ALGAAS-ALAS-GAAS DOUBLE-BARRIER MULTIPLE-QUANTUM-WELL INFRARED DETECTOR

We have studied both the molecular-beam epitaxy (MBE) and metal-organi c chemical vapour deposition (MOCVD) grown AlGaAs-AlAs-GaAs double bar rier multiple quantum well structures for 3-5 mu m infrared (IR) photo detector application. The intersubband absorptions of these samples we re measured al the Brewster angle as well as through a multipass 45 de grees wedge waveguide. In the former case, we have also studied the po larisation dependence of the IR transmission. The MBE grown sample has an absorption at about 3.1 mu m, while the absorption peak for the MO CVD sample is shifted slightly, depending on the wafer location. The l ow temperature photoluminescence peaks show a significant shift when t he probe position is moved across the MOCVD wafer along the gas how di rection, owing to thickness non-uniformity. This variation was also co nfirmed by double crystal X-ray diffraction data. Theoretically, we ha ve carried out a bound and quasibound state energy calculation for the se structures as a function of well width and related them to the expe rimental results. In addition, the IR photoresponse for the MBE grown sample at about 80 K has been measured for IR photodetector applicatio n.