Corrugated quantum well infrared photodetectors

A new light coupling geometry for quantum well infrared photodetectors (QWIP), which is referred as the corrugated- QWIP or the C-QWIP, has been demonstrated. The coupling scheme is based on the total internal reflection at a number of slanted sidewalls created within a detector pixel. The structure was found to be able to couple normal incident light efficiently into the detector with concomitant reduction in the dark current. For a C-QWIP with thinned substrate, the background photocurrent to the dark current ratio is improved by a factor of 4.9 compared with the edge coupling. The coupling scheme does not show significant wavelength and size dependence, and is therefore suitable for multi-color or high resolution thermal imaging. With these characteristics, a C- QWIP behaves as a detector with normal incident absorption. Because of its simple fabrication procedures, the manufacturability of the detector arrays can be greatly improved.