Spicer’s absorption diffusion model is extended to analyze Schottky photodiodes which possess special characteristics. The model describes the generation of minority carriers by optical absorption in the bulk of a semiconductor material. The magnitude and shape of the spectral response for a minimally depleted device is found to depend on the rate of variation of the absorption coefficient with wavelength on the thickness of the absorbing region T and on the minority carrier’s diffusion length l. Narrow spectral response can exist in this device only in the wavelength region wherein the absorption coefficient α is rapidly changing. A combination of high quantum efficiency with sharp tuning is found to exist.
John R. Sizelove and John A. Love, III, "Narrow Spectral Response Schottky Photodiodes," Appl. Opt. 6, 1777-1780 (1967)