Corrugated infrared hot-electron transistors

The sensitivity of a focal plane array in terms of the noise equivalent temperature difference ultimately depends on the detector photocurrent to dark current ratio r(I). In this work, we have integrated two approaches in the quantum well technology that can increase r(I) into a single detector structure. The new detector is referred to as the corrugated infrared hat-electron transistor (CI-HET). In this detector structure, an energy filter is grown next to a standard quantum well infrared photodetector (QWIP) for more selective collection of the photocurrent. At the same time, corrugated structures are physically fabricated into the detector pixel to increase light absorption in the QWIP. With this combined approach, r(I) is able to increase by more than a factor of five compared to a standard QWIP. in addition, the new structure reduces the total current of the detector to a level that is suitable for signal integration. (C) 1998 American Institute of Physics. [S0003-6951(98)02835-6].