Fabrication And Photodetecting Performance Of MoS₂/Si Pn Junction

Due to their unique microstructural characteristics and excellent properties,molybdenum disulfide?MoS₂?layered semiconductor materials have attracted much attention in recent years.Compared to graphene materials,MoS₂-based materials,from monolayers to bulk,have obvious band gap.Thus,MoS₂ has been considered as the basic semiconductor material in developing next-generation electronic devices.Based on mature Si-based microelectronics technology,the heterojunction devices composed of MoS₂ film and Si semiconductor could supply simple technique route to realize the integration of Si-based multifunctional devices.In this work,MoS₂ thin films were deposited on Si substrates using DC magnetron sputtering technique and MoS₂/Si heterojunctions were fabricated.Further,the photosensing characteristics of MoS₂/Si heterojunction devices were studied and their mechanisms were revealed by energy-band diagram near the interface.Firstly,the effect of the thickness of film and substrates temperature for the MoS₂film and the electrical performance of MoS₂/Si devices were studied.The results indicate that the devices with the minimum series resistance show a good rectification characteristics when the substrate temperature was 300?C and the thickness of film was40 nm and the rectification can be up to 80.Secondly,the MoS₂ films were deposited on SiO₂/Si and Si substrates by using DC magnetron sputtering technique.The quality of pn junction and photodetection characteristics of both devices were studied.The results indicate that the devices with SiO₂ buffer layer show a high ideality factor,an extremely high on/off rate?60?and a ultra-fast response speed?⁴?s?.Then,metal Pd were incorporated into MoS₂ films to modulate the semiconductor characteristics of the films and the performance of Pd/Pd:MoS₂/SiO₂/Si heterojunction as self-powered photodetectors were studied.The results indicates the device performance shows wide photosensing range,good stability,high photoresponse and detec tion.Thus,the fabricated Pd/Pd:MoS₂/SiO₂/Si heterostructures have large potential application in the area of developing new-type photodetectors.At last,the photosensing performance of ITO/Pd:MoS₂/SiO₂/Si heterojunction was studied.Due to the high conductivity and incident light transmittance of ITO electrode,the responsivity of the ITO/Pd:MoS₂/SiO₂/Si heterojunction devices was further enhanced to 1200 mAW^-1.This performance is much better than the value for the reported MoS₂-based self-driven photodetector.In summary,through deep study of MoS₂/Si film heterojunction and the photovoltaic device performance,new choice of materials can be provided for multi-functional electronic devices.Further,the interfacial energy band modulation and coupling of the MoS₂/Si heterojunction were clarified in this thesis.