Normal incident long-wavelength quantum well infrared photodetectors using electron intersubband transitions

Abstract

Grating-free quantum well infrared photodetectors (QWIPs) for 8-10 mu m applications have been fabricated. The QWIPs fabricated with InGaAs/GaAs quantum wells show excellent performance with normal-incident infrared radiation. A detectivity of 2 x 10(10) cm Hz(1/2)/W and a responsivity of 0.23 A/W have been obtained for these devices. The devices were compared with QWIPs with 1D and 2D surface gratings. No significant improvement in responsivity is observed for devices with 1D gratings. Devices with 2D gratings have significantly higher peak responsivity but only in a very limited spectral range. The GaAs/AlGaAs QWIPs in the similar spectral range have also been fabricated and, however, shown much weaker TE absorption. (C) 1997 American Institute of Physics.