Injection photodiode based on an $n$-CdS/$p$-CdTe heterostructure

The possibility of developing injection photodiodes with a tunable/reconfigurable photosensitivity spectrum in the spectral range of 500–800 nm based on an $n$-CdS/$p$-CdTe heterostructure is shown. It is established that such a structure in the short-wavelength region $\lambda$ = 500 nm has the highest spectral sensitivity $S_\lambda\approx$ 3 A/W in the forward direction at a bias voltage of $V$ = +120 mV and $S_\lambda\approx$ 2 A/W in the reverse direction at a bias voltage of $V$ = -120 mV. The integrated sensitivity of the device is $S_{\mathrm{int}}$ = 2 400 A/lm under illumination with white light $E$ = 3 $\times$ 10$^{-2}$ lx, at a bias voltage of $V$ = +4.6 V, and temperature of $T$ = 293 K. Upon illumination with the monochromatic light of an LG-75 laser with the wavelength $\lambda$ = 625 nm, $S_{\mathrm{int}}$ = -1400 A/W (illumination power $P$ = 18 $\cdot$ 10$^{-6}$ W/cm$^2$, bias voltage $V$ = +4.6 V, and temperature $T$ = 293 K). High values of $S_\lambda$ and $S_{\mathrm{int}}$ provide the highly efficient transformation of light energy into electrical energy at low illumination levels ($P<18$ $\times$ 10$^{-6}$ W/cm$^2$)