HgCdTe (MCT) LWIR arrays by MOCVD on GaAs

MOCVD growth of MCT on GaAs or GaAs/Si provides a means of obtaining large areas of high quality material at low cost for IR array processing. The authors report results from LWIR arrays on MCT grown on GaAs via a CdTe buffer. The arrays were processed by a modified planar technology. The n on p junction is formed by Hg diffusion through a mask on p-type layers. Sputtered passivation layers were used to reduce surface recombination effects. Typical photodiodes had R₀A products of 10 Ωcm² at 77 K (λ_co 11 μm). These were obtained with high quantum efficiencies (greater than 70%) and 77 K detectivities of 1.1×10¹¹ cmHz^1/2 /W. Results from arrays of photodiodes are included