MOLECULAR-BEAM EPITAXIAL-GROWTH AND PERFORMANCE OF INTEGRATED MULTISPECTRAL HGCDTE PHOTODIODES FOR THE DETECTION OF MID-WAVE INFRARED RADIATION

In situ doped HgCdTe two-color detectors with the n-p-n geometry were grown by molecular beam epitaxy, for the simultaneous detection of two closely spaced bands in the mid-wave infrared spectrum. The average n ear-surface etch pit densities in these layers were 5 x 10(6) cm(-2), which is a factor of 10 higher than that observed for the lattice-matc hed growth of Hg1-xCdxTe (x = 0.22) layer on Cd0.96Zn0.04Te substrates . The 0.04% lattice mismatch between the Hg1-xCdxTe (x = 0.35) epilaye r and the Cd0.96Zn0.04Te substrate produces plastic deformation of the epilayer which results in an increased dislocation densities in the e pilayer. The alloy composition across the device structure along the g rowth direction was determined by secondary ion mass spectrometric ana lysis, and deviated by less than 1% from the target. The device struct ures were processed as diodes with the mesa architecture and tested. T he spectral response of the detectors at 77 K was characterized by sha rp turn off at 3.7 and 4.4 mu m. R(0)A values in excess of 1 x 10(6) O mega cm(2) and quantum efficiencies greater than 75% were measured for diodes in each band. (C) 1998 Elsevier Science B.V. All rights reserv ed.