Modeling of the zero-bias resistance-area product of long wavelength infrared HgCdTe-on-Si diodes fabricated from molecular beam epitaxy-grown epitaxial layers

The electrical effects of dislocations has been studied by modeling zero-bias resistance-area product (R₀A) of long wavelength infrared diodes fabricated in molecular beam epitaxy (MBE)-grown HgCdTe-Si epitaxial films. Results show that dislocations influence both 40 K and 78 K R₀A products in high dislocation density (HgCdTe/Si) material. In low dislocation density samples (HgCdTe/CdZnTe), the variations in 78 K R₀A are limited by the composition (x) variations in Hg_1-xCd_xTe material, whereas dislocation contribution dominates the variations at 40 K. The origin of relatively large spread in 40 K R₀A in both types of samples is traced to the statistical variations in the core charges of dislocations. It is concluded that additional alternatives besides the reduction of dislocation density (such as control of core charges), may also need attention in order to make Si a viable substrate material for the growth of HgCdTe epitaxial layers suitable for devices operating at 40 K.