MOVPE growth of HgCdTe for high performance 3-5 μm photodiodes operating at 100-180K

New results are reported on the growth of high performance medium wavelength infrared (3-5 mu m) (MWIR) HgCdTe photodiodes in the three-layer P-n-N configuration. The detector structures were grown in situ by metalorganic vapor phase epitaxy (MOVPE) on (211)B oriented CdZnTe substrates. The mobilities of the single n-type layers with x-values of similar to 0.30 are in the range of (3-4.5) x 10(4) cm(2)/V-s at 80K. The lifetimes on unpassivated films range from 1-5 and 4-10 mu s at 80 and 180K, respectively, which are within a factor of two or less of the lifetimes calculated for Auger-l and radiative recombination. The P-n-N films were processed into variable-area backside-illuminated diagnostic arrays and tested for quantum efficiency, spectral response, R(D)A, I-V curves and 1/f noise in the 120-180K range. The internal one-dimensional quantum efficiencies are in the range of 85-100%. The optical collection lengths are typically similar to 25 mu m. I-V curves showed that diffusion current is the dominant junction current mechanism for temperatures greater than or equal to 100K. R(0)A values are at the one-dimensional limit for n-side diffusion currents over the 100-180K range. 1/f noise was measured to be very low at 120K and is the same as that measured in similarly processed arrays from recent LPE grown P-on-N heterojunctions. The results demonstrate that MOVPE growth can be used for large area, high performance MWIR HgCdTe detector arrays operating in the 120-180K temperature range.