Optimization of lamellar gratings for quantum-well infrared photodetectors

This article presents the results of a self-consistent model of midinfrared intersubband absorption in n-doped quantum wells, which are optically coupled by one-dimensional reflective gratings. In the vicinity of the cutoff of the grating, multiple reflections at the well-barrier interfaces play an important role. With an optimized grating, a near-unity absorption quantum efficiency is predicted for the transverse-magnetic polarization. The influence of the top contact on the design of the grating is studied. Performances of standard detectors are compared to those using an additional aluminum-arsenide confinement layer below the bottom contact. Finally, the influence of the number of wells on the performance of the device is investigated. (C) 2000 American Institute of Physics. [S0021-8979(00)01318-9].