C-QWIP focal plane array sensitivity

Abstract

We are developing corrugated quantum well infrared photodetector (C-QWIP) technology for long wavelength applications. A number of large format 1024 × 1024 C-QWIP focal plane arrays (FPAs) have been demonstrated. The measured quantum efficiency η is ranging from 15 -37%, depending on the detector type, doping density and number of quantum wells in the detector material. The photoconductive gain is between 0.07 and 0.19, while the spectral width is between 1.5 and 3.5 microns. Despite the large integrated η of the C-QWIPs, the number of collected photoelectrons can be limited in shorter cutoff, small pixel FPAs under high speed operation. In this case, the read noise will have a large impact on the system sensitivity. In this paper, we will discuss the detector model, the measured pixel characteristics, and the effects of read noise on the FPA performance. Our analysis shows that the tolerable read noise improves with the cutoff wavelength. For example, to achieve a sensitivity of 20 mK at 2 msec integration time, the respective read noise will be 1000, 2000, 3000, and 4000 e¯ at λ c = 8. 8, 9.4, 10.7 and 11.7 μm. This analysis will help to determine the read noise requirement for the C-QWIP FPAs.