Technologies for Data Evaluation and Electronic Scientific Articles

Not Available Photodetectors operating at 8-15 um and beyond are of great importance for commercial and military applications in infrared (IR) thermal imaging. InAs/InGaSb type-II quantum wells (QWs) have advantages over HgCdTe for applications requiring higher temperature and longer wavelength operation. The type-II QW photodiodes would have comparable quantum efficiency and smaller dark current due to a larger effective mass and enhanced lifetimes due much slower Auger recombination rates, and hence much longer carrier lifetime. Through careful bandgap engineering, we have suppressed the Auger coefficient by a factor > 8 for 4.5-um type-II QW mid-IR lasers at 300 K. Recently, p-i-n photodiodes using InAs/InGaSb type-II QWs have achieved detectivities larger than 1 x 10 10 cmHz 1/2/W at 8.8 um and 78 K, with a peak detectivities of 2.1 x 10 10 cmHz 1/2/W at 6 um. We have studied InAs/InGaSb type-II QW photoconductors. With improved MBE growth technology, we have improved the responsivity of type-II photoconductors by a factor 50, due to the improved interface quality and material quality, and hence the better optical properties and longer carrier lifetime. Currently, we have demonstrated among the best performance of photoconductors using III-V materials up to 14 um. In the program, we will develop large two-dimensional arrays of IR photodetectors based on InAs/InGaSb type-II QWs at 8 to 20 um.