Self-driven heterostructure photodetector of sputtered CZTS film on c-Si with an inverted pyramid structure

Abstract

Ag has been incorporated into the CZTS film through post-doping by magnetron sputtering to decrease the CuZn anti-site defect. Efforts have been dedicated to optimize the Ag sputtering time and 60 s will be the best as surveyed from the SEM, XRD and Raman spectra. Then the broad-band self-driven heterostructure photodetector has been manufactured by combining the CZTS and inverted pyramid n-Si (IP n-Si). The device represents the first-rank property under the irradiation of 5 mW, 780 nm LED with 0 V bias with the responsivity and detectivity of 7.2 mA/W and 4.98 × 1010 Jones respectively. The device can persist excellent linearity when enduring a 40 mW-80 mW, 980 nm NIR laser with 0 V bias. The comprehensive performance becomes the best under the irradiation of a 50 mW laser. The responsivity and detectivity are 1.22 mA/W and 1.98 × 1010 Jones. The device can also work stably as the laser changes from 1 Hz to 15 kHz. The rise time and decay time are 93.3 μs and 141.0 μs respectively. These results open up an innovative application for CZTS to build a broad-band self-driven photodetector as a window-layer.