Performance of corrugated quantum well infrared photodetectors

Corrugated quantum well infrared photodetectors (C-QWIPs) utilize total internal reflection to couple normal incident light into the detectors. In this work, we performed a systematic study on C-QWIPs with cutoff wavelength lambda(c) ranging from 5 to 17.3 mu m and device areas ranging from 50 x 50 mu m(2) to 500 x 500 mu m(2). We found that the coupling efficiency of the C-QWIPs is, indeed, independent of both the detection wavelength and the pixel size, as expected. Compared to devices with a standard 45 degrees edge coupling, the C-QWIP increases the background photocurrent to a dark current ratio by a factor between 2.4 and 4.4, thereby increasing the background limited temperature by 3-5 K. At the same time, the detectivity D* is also increased by a factor around 2.4. For lambda(c) = 9.4 mu m, the peak detectivity D-p* and the blackbody detectivity D-bb* at 78 K are measured to be 4.5 x 10(10) cm root Hz/W and 4.5 x 10(9) cm root Hz/W, respectively. (C) 1997 American Institute of Physics.