Novel molecular-beam epitaxially grown GaAs/AlGaAs quantum well structures for infrared detection and integrated optics at 3-5 and 8-12 mym.

Two novel molecular-beam epitaxially grown quantum well device structures for 3-5 and 8-12 Mym photodetection and integrated optics are presented, both of which rely intimately upon the ability of molecular-beam epitaxy to precisely reproduce demanding layer sequences. The first structure combines single-mode infrared waveguiding, grating- coupling, and intersubband absorption at 10 Mym in a GaAs/AlGaAs multilayer structure. The second structure demonstrates the feasibility of extending the operating wavelength range of GaAs/AlGaAs infrared detectors into the 3-5 Mym atmospheric window by incorporating ultrathin AlAs tunnel barriers. Both growth-induced and intentional inequivalences in the tunnel barriers are found to lead to enhanced photovoltaic detection in these latter devices.