High quantum efficiency II-VI photodetectors for the blue and blue-violet spectral range

We have fabricated II-VI wide gap hetero PIN photodiodes made of ZnMgSSe wi th excellent structural and interface quality and with a high external quan tum efficiency of about 60%, which is close to the theoretical limit. The i nternal quantum efficiency reaches peak values of more than 80%. The onset of the sensitivity is very sharp, leading to a quantum efficiency less than 10(-4) at wavelength 60 nm below the band gap. Using the wide range of ene rgy gaps from 2.68 to 3.1 eV, it is possible to fabricate wavelength select ive detectors if the energy gap of the top p-type layer is chosen slightly higher than that of the intrinsic zone. The dark current is below 0.1 pA/ m m(2). In the low signal limit, the noise equivalent power can be estimated to be below 10(-15) W root Hz/mm(2) at the peak external quantum efficiency , surpassing ultraviolet optimized Si detectors. (C) 1998 American Institut e of Physics. [S0003-6951(98)04550-1].