Reduction Of Surface Leakage Current In Cd 0.2 Hg 0.8 Te Photodiode

The surface leakage current of Cd0.2 Hg0.8Te photodiodes has been reduced by forming a wide gap epitaxial layer on the surface. CdHgTe double-layers consisting of p-CdxHgl_xTe (x>0.2)/p-Cd0.2Hg0,8Te were grown by liquid phase epitaxy on CdTe substrates. The hole carrier concen 3tration and m 1obility, obtained from van der Pauw Hall measurement at 77K, were 9x1015cm-3 and 6x102cm2V-15-, respectively. The p-n junctions were formed by removing the wide gap layer of 100/i m diameter to reach p-Cd0.2Hg0.8Te followed by the Indium diffusion in p-Cd0.2Hg0.8Te. The R0A products of the photodiode with and without the wide band gap layer were 9.1Q cm ² (λ c=11μ m) and 2.00 cm2 (λ c=10μ m) at 77K, respectively, which confirm the effect of the wide gap layer on the surface leakage current reduction.