Research Of Interface Modification And Photodetection Property Of Graphene/Silicon Heterojunction

Graphene?Gr?is a two-dimensional material with unique optical and electrical properties,it has been applied in the field of photoelectric detection by researchers.Gr/Si heterojunction photodetectors have attracted the attention of researchers due to their simple preparation process and wide detection band in the visible-near infrared light range.However,due to the weak light absorption characteristics of Gr and Si,the performance of Gr/Si heterojunction photodetectors will be limited to some extent?Transition metal sulfur compounds?TMDs?have unique photoelectric properties and can be stacked and assembled freely by Van der Waals force.Therefore,the interface of Gr/Si heterojunction can be modified by TMDs,which can effectively improve the photoelectric detection performance.So the main research of this paper is as follows:?1?Research on the transfer of two-dimensional materials.Firstly,the wet transfer of Gr was improved.During the transfer process,the secondary spin-coated PMMA method has improved the problem that Gr is prone to damage.And annealing the sample in air can effectively remove PMMA.Secondly,a combination of mechanical peeling and dry transfer was used to successfully prepare a large-area multilayer PdSe₂ material.These two processes make preparations for the fabrication of heterojunction devices.?2?Firstly,the silicon nanowire structure was prepared,and the Gr/Si heterojunction interface was modified with the silicon nanowire structure.In order to carry out comparative test,Gr/Planar Si and Gr/SiNWs heterojunction photodetectors were prepared respectively.The experimental results show that both devices have obvious photoelectric response in the visible-near infrared light band,and the device with silicon nanowire structure for interface modification has a maximum responsivity of 80%and a normalized detection rate increased by an amount level.?3?In order to study the influence of PdSe₂ material as the interface modification layer of Gr/Si device on the performance,Gr/PdSe₂/Si and Gr/Si heterojunction photodetectors with micron size junction area were prepared respectively,and the performance of the two devices was compared and analyzed.The detection bands of both devices range from 450nm to 1000nm,and both have the highest responsivity at 650nm.After using PdSe₂ material to modify the interface of Gr/Si heterojunction,the performance of the heterojunction has been greatly improved.The highest response of Gr/PdSe₂/Si heterojunction is about 56 A/W,which is two orders of magnitude higher than that of Gr/Si heterojunction,and the detection rate has also increased two orders of magnitude.Moreover,due to the introduction of PdSe₂,the heterojunction photodetector has a high quality interface,so the Gr/PdSe₂/Si heterojunction shows obvious photovoltaic effect.However,due to the introduction of multi-layer PdSe₂ material,the transition time of the carrier becomes longer,resulting in a longer response time?28.38ms?of the heterojunction photodetector.Finally,the stability of the two heterojunctions was tested.It was found that the performance of the Gr/PdSe₂/Si heterojunction had almost no change after 28 days in the air and the photoelectric response of the Gr/Si heterojunction became very weak.Therefore,the Gr/PdSe₂/Si heterojunction has high stability after the introduction of PdSe₂ as the interface modification layer.