Fabrication And Performance Study Of Flexible Silicon-based Photodetectors

Ultraviolet-infrared broad-spectrum photodetectors have an important role in imaging,biomedical testing,environmental monitoring,sensing and free-space optical communications.With the update and iteration of science and technology,the demand for high performance and multifunctional integration has prompted the development of traditional photodetectors along the direction of composite photodetectors coupled with ferroelectric,pyroelectric and piezoelectric effects.Cadmium sulfide(CdS),an important member of the third generation of semiconductors,is a semiconductor material with simultaneous photoelectric,piezoelectric and pyroelectric properties and is an important candidate for the preparation of composite photodetectors.The performance of photodetector devices is inextricably linked to the properties of the material itself,the micro and nano structure and growth quality as well as the hierarchical architecture of the device.In this paper,CdS micro-nanostructures with different morphologies were prepared by radio frequency(RF)magnetron sputtering technology;several low-cost,high-performance broad spectrum response photodetectors were prepared by combining CdS with silicon(Si)materials;In addition,the performance of heterojunction photodetectors was enhanced by introducing the pyro-phototronic effect and piezo-phototronic effect of wurtzite CdS,enabling the development of low-cost,low-energy,multifunctional integrated photodetectors.Firstly,we fabricated a traditional photovoltaic Si/CdS heterojunction photodetector on a rigid Si substrate by RF magnetron sputtering technology.The devices have good rectification characteristics by forming stable heterojunctions with p-Si and n-CdS,and the device performance is basically unchanged after repeated measurements,and the devices exhibit good self-powered detection performance in a wide spectral range from 365 nm to 980 nm.Secondly,on this basis,we prepared high-quality,coarse and uniform wurtzite-structured CdS nanorods with a length of about 1 μm by RF magnetron sputtering.By introducing a pyro-phototronic effect formed by coupling the pyroelectric effect,the photoelectric effect and the semiconductor properties of CdS nanorods,the Si/CdS self-powered heterojunction photodetector exhibits a wide spectral detection capability from 365 nm to 1310 nm,and the detection range exceeds the bandgap limit of the material itself.In addition,under 980 nm laser irradiation,the rise and fall times of the detector are 70 μs and 90 μs,respectively,which has a very fast response speed.The photoresponsivity and specific detectivity are enhanced by 23.3 times under the action of pyro-phototronic effect compared with the performance based on photovoltaic effect alone.Finally,a flexible photodetector is designed based on Si/CdS self-powered heterojunction photodetector,which significant rectification characteristics in the dark state and enables a wide spectral detection of ultraviolet to near infrared light.The performance of the photodetector has been significantly improved by introducing the piezo-phototronic effect formed by the coupling of the piezoelectric effect of the CdS nanorods with the photoelectric effect and semiconductor characteristics.When an external compressive strain is applied to the device,the photocurrent of the device is significantly improved.These results indicate that the pyro-phototronic effect and piezo-phototronic effect can greatly enrich the functions of photodetectors and improve the performance of photodetectors.