Wide bandwidth 10.6 µm (Hg,Cd)Te photodiodes for infrared heterodyne applications

This paper reports the lowest noise equivalent power (NEP), approximately 6.2 × 10^-20watts/Hz, ever measured for 10.6 µm n⁺-n^--p⁺(Hg,Cd)Te photodiodes at a frequency of 1750 MHz and at 77 K, as determined by blackbody heterodyne radiometry techniques (1-3). This value of NEP corresponds to an effective heterodyne quantum efficiency of 30%. The devices were fabricated by means of planar processing techniques and capacitance-voltage measurements revealed that the junctions were abrupt and contained a donor concentration in the n^-layer of approximately 4.0 × 10¹⁴to 1.0 × 10¹⁵cm^-3.