A diffusion model for the internal photoresponse of PtSi/p-Si Schottky barrier diodes

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Abstract
A one‐dimensional diffusion model describing the variation of the internal photoyield per absorbed photon of thin‐film platinum silicide/p‐type silicon Schottky barrier diodes with silicide layer thickness and incident photon energy is developed. In addition to providing a simple result, the diffusion formulation of the problem shows very clearly the relative importance of scattering processes and the barrier transmission probability in the determination of the device photoresponse. The model is demonstrated to accurately describe the available experimental data if the inelastic scattering length in the thin PtSi film is assumed to be ∼4000 Å. The application of this model in conjunction with optical absorption calculations to determine the total quantum yield per incident photon and the optimum silicide thickness as a function of wavelength are also described. This procedure predicts optimum film thicknesses on the order of tens of angstroms, coinciding with experimental observations.