HgCdTe detectors operating above 200 K

This paper reports progress with work aimed at using HgCdTe detector arrays at temperatures above 200 K where cooling is possible with thermo-electric coolers. Both theoretical analysis and calculations based on the detector dark currents indicate that useful performance should be obtainable in this temperature range. However, measurements on the performance of two-dimensional arrays show that the thermal sensitivity degrades rapidly for temperatures above 200 K. The reduction in performance at higher temperatures is shown to be mainly due to increasing 1/f noise as the temperature increases. The noise is characterized as a function of bias and temperature and this is used to predict the noise equivalent temperature difference (NETD) as a function of temperature. We describe an approach for producing two-dimensional arrays based on biasing the detector elements at close to zero bias so that the 1/f noise is minimized. A camera based on this concept is described and an example of the imaging performance is shown.