Measurement of the steady-state minority carrier diffusion length in a HgCdTe photodiode

A new method is reported for estimating the steady-state effective minority carrier diffusion length. The diffusion length is determined by measuring photocurrents which decrease exponentially with the distance between the junction edge and the region into which environmental infrared light penetrates. The region exposed to infrared radiation can be defined using an optical shadow mask. Using this method, the steady-state effective minority carrier diffusion length of photodiodes fabricated on p-type bulk Hg0.7Cd0.3Te was determined to be 19 mu m at all points on the wafer.