Pb1-xEuxSe photodiodes for the 3 - 5 mym ranges.

A series of five photodiode detectors have been fabricated using MBE growth techniques from the ternary compound PbEuSe with values of x ranging from 0 to about 10 mol. %. With the europium concentrations the cut-off wavelength can be tuned from 6.7 micrometer (x - 0) to 2.7 micrometer (x = 0.1) at 95 K. With the growth of a graded cap layer the spectral quantum efficiency was increased by aproximately a factor 2 compared with diodes previously fabricated without the cap layer. RoA and spectral quantum efficiency values were determined over a temperature range of 95 - 300 K. The measured values of RoA are compared to calculated values of RoA based on a diffusion limited model and an attempt is made to explain discrepancies.