Piezo-Phototronic Effect on Performance Enhancement of Anisotype and Isotype Heterojunction Photodiodes

The piezo-phototronic effect is confirmed as a promising methodology to optimize the performance of optoelectronic devices. However, not only positive effects, but also negative effects may be produced in some types of photodiodes (PDs) by the piezo-phototronic effect, resulting in the restriction of the PDs' photoresponse performance enhancement. In order to obtain the largest possible photoresponse performance enhancement, it is essential to investigate how the piezo-phototronic effect influences the photoresponse performance of PDs with different device configurations and structures. Here, the piezo-phototronic effect on the photoresponse performance enhancement of anisotype (p-Si/n-ZnO) and isotype (n-Si/n-ZnO) heterojunction PDs is thoroughly investigated. The experimental results show that the piezo-phototronic effect induced improvement of the p-Si/n-ZnO heterojunction PD is much larger than that of the n-Si/n-ZnO heterojunction PD. The energy band diagrams under compressive strains are carefully analyzed, revealing that two positive effects are introduced to the p-Si/n-ZnO heterojunction PD, whereas one positive and two negative effects are introduced to the n-Si/n-ZnO heterojunction PD by the piezo-phototronic effect. This work presents an in-depth understanding about the piezo-phototronic effect on the photoresponse performances of PDs with different device configurations and structures.