The operating temperature is an important consideration. Refrigeration becomes more costly and difficult as the operating temperature is lowered. For many applications the detector operating temperature should be high enough so that relatively low-cost refrigeration (such as liquid nitrogen at 77 K) can be used. This requirement of 77 K operation eliminates the possible use of extrinsic silicon detectors, which must be cooled to less than 30 K, from many applications.
Accetta, J.S., and D.L. Shumaker, eds. 1993. The Infrared and Electro-Optical Systems Handbook, Vol. PM10. Society of Photo-optical Instrumentation Engineers. Bellingham, Washington: SPIE Press.
Mooney, J.M., F.D. Shepherd, W.S. Ewing, J.E. Murguia, and J. Silverman. 1989. Responsivity nonuniformity limited performance of infrared staring cameras. Optical Engineering 28(11):1151–1161.