CdTe/HgCdTe indium-diffused photodiodes

CdTe/HgCdTe structures have been prepared by MBE deposition of high resistivity CdTe on bulk p-type Hg _{1- x}Cd _xTe ( x = 0.295). Diodes were produced by diffusion from indium dots evaporated on the CdTe surface. The I-V characteristics are diffusion-limited down to a temperature of 160K. The C-V characteristics indicate a built-in potential of 0.2 V. The diodes operate as photovoltaic detectors due to lateral collection around the diffused region, showing a spectral response between 0.9 and 5 μm. The lateral collection effect has been used to measure the minority carrier diffusion length in the HgCdTe substrate and calculate the theoretical saturation current as a function of temperature; good agreement with the experiment was found.