Piezo-phototronic effect-modulated carrier transport behavior in different regions of a Si/CdS heterojunction photodetector under a Vis-NIR waveband

The piezo-phototronic effect, as a three-way coupling effect of piezoelectricity, semiconductor and optical excitation in piezoelectric semiconductors to improve the performance of optoelectronic devices, has a wide range of applications in various fields. However, under different light illumination conditions, the piezo-phototronic effect would have different effects on the optoelectronic performance due to the different photo-generated carrier excitation regions. Here, the piezo-phototronic effect is utilized to modulate the carrier transport behavior of a p-Si/n-CdS heterojunction PD during the optoelectronic process in a broadband range from visible to near-infrared light. The strain-induced piezo-charges significantly improve the photoresponse performance of the heterojunction PD. The photoresponsivity increases by 1867% under −0.35‰ strain under 808 nm light illumination, with a remarkable reduction in the rise and fall times to ∼2.1 ms (reduced by 83.3% and 50.0%, respectively). However, since the photo-generated carriers are produced only at the n-CdS side under 442 nm light illumination, the photoresponse performance is greatly weakened by the piezo-phototronic effect. The corresponding working mechanism of the piezo-phototronic effect on the heterojunction photodiode under different light illumination conditions is proposed in detail. These results provide an in-depth understanding about the piezo-phototronic effect, which would enable more efficient utilization of the piezo-phototronic effect in optoelectronic devices.