MONTE-CARLO CALCULATIONS OF QUANTUM YIELD IN INHOMOGENEOUS PTSI P-SI SCHOTTKY BARRIERS/

Monte Carlo calculations of quantum yield in PtSi/p-Si infrared detect ors are carried out taking into account the presence of a spatially di stributed barrier potential. In the 1-4 mu m wavelength range it is fo und that the spatial inhomogeneity of the barrier has no significant e ffect on the overall device photoresponse. However, above lambda = 4.0 mu m and particularly as the cut-off wavelength (lambda approximate t o 5.5 mu m) is approached, these calculations reveal a difference betw een the homogeneous and inhomogeneous barrier photoresponse which beco mes increasingly significant and exceeds 50% at lambda = 5.3 mu m. It is, in fact, the inhomogeneous barrier which displays an increased pho toyield, a feature that is confirmed by approximate analytical calcula tions assuming a symmetric Gaussian spatial distribution of the barrie r. Furthermore, the importance of the silicide layer thickness in opti mizing device efficiency is underlined as a trade-off between maximizi ng light absorption in the silicide layer and optimizing the internal yield. The results presented here address important features which det ermine the photoyield of PtSi/Si Schottky diodes at energies below the Si absorption edge and just above the Schottky barrier height in part icular.