Quantum yield of metal-semiconductor photodiodes

A theoretical expression for the quantum yield of metal-semiconductor photodiodes is derived that takes into account the effects of the presence of an inversion region. This expression predicts a sharp decrease of the quantum yield in the short wavelength regime, in contrast with previous theoretical predictions. Applied to a Au-nSi Schottky-barrier photodiode, our theory displays the functional dependence with which the quantum yield increases with increasing doping densities for short wavelengths and decreases with increasing doping densities for long wavelengths. Excellent agreement is demonstrated between theoretical predictions and experimental data in the short-wavelength regime (i.e., for 0.4<λ<0.6 μm).