HgCdTe/CdTe mosaics for high temperature operation

The performance of backside-illuminated HgCdTe/ CdTe photodiode arrays at temperature range of 170- 200K is presented. Electro-optical characterizations of these 3-5 µm detectors show excellent spectral response uniformity (Δλco= ± 0.03 µm) and high RoA product. Devices with spectral cut off of 4.3 µm at 200K exhibit RoA values of 15 Ω cm²at 200K and 150 Ω cm²at 172K. These values are a factor of 3-5 times higher than the expected RoA for bulk HgCdTe with similar material parameters. The increase is accounted for by the limited diffusion volume configuration obtained by the ∼10 µm thick liquid phase epitaxial active layer. The resulting device structure and performance appears to be well suited for thermoelectrically cooled hybrid focal plane applications.