Silicon differential photodetectors. Technology, characteristics, application

A silicon-based photodetector containing two identical $n^+$–$p$-photodiodes is described. One of the photodiodes had a wide spectral response with high sensitivity in the ultraviolet region. The sensitivity of the second was reduced in the short-wavelength part of the spectrum by creating additional recombination centers in the near-surface region by implanting As ions. The spectral sensitivity of the differential signal obtained by subtracting photocurrents had a pronounced short-wavelength characteristic. The long-wavelength limit of the spectral range in terms of the $\lambda_{0.5}$ level, depending on the doping dose, was in the range of 0.37–0.47 $\mu$m. The sensitivity maximum corresponded to $\lambda_{\mathrm{max}}$ = 0.32–0.37 $\mu$m. The electrical and noise characteristics of the photodetector are given. The possibility of using differential photodetectors as two-color ones is shown.