Reaserch Of ZnSe Film/Graphene Hybrid Based Photodetector With Short Channel

In recent years,photodetectors have attracted wide attention at home and abroad.Photodetector based on the film structure has a greater advantage than which based on one-dimensional(1D)nanostructure in stable performance.However,the grain boundary of nanocrystalline particles has a scattering effect on carriers,which makes the performance of photodetectors greatly reduced.Graphene with high carrier mobility is combined with semiconductor film to form heterojunction,and the performance of the photodetector has been greatly improved compared with the pure film based photodetector.Further,by shortening the length of the electrode channel,the recombination rate of the photoelectron hole pair can be reduced,so that more carriers are migrated quickly,and the transport of the external circuits will be involved,which brings more cycle times,and can also greatly improve the performance of the photodetector.(1)Using photolithography technology to realize the graphics of the device,5?m channel ZnSe film/graphene hybrid based photodetector was prepared by combining the graphene and the ZnSe film deposited by electron beam coating,The photodetector prepared in this experiment shows a high responsivity of 6.1×10~6 A/W and the maximum photocurrent is 21.2?A.This is a great improvement compared with the pure ZnSe film based photodetector of photocurrent of pA level,reflecting the change of graphene to the performance quality of the device.(2)We propose a simple and low cost method,that is,using ZnS nanowire as a mask and constructing nanoscale channel between electrodes,which is applied to the fabrication of photodetector.In this experiment,a 70 nm channel ZnSe film/graphene hybrid based photodetector was constructed.It possess an ultrahigh responsivity up to 1.2×10~9 A/W and a response time of 50 ms,the maximum photocurrent is 240?A.Finally,in order to verify the relationship between channel length and the performance of photodetectors,we deposited ZnS films on ZnS nanowires and obtained ZnS nanowires with different diameters.185 nm and 380 nm channel ZnSe film/graphene hybrid based photodetectors were fabricated as control group.Comparing the responsivity and response time of the four devices,it is obvious that with the decrease of channel length,the performance of the photodetector,such as response degree,response rate,detection rate,external quantum efficiency and so on,can be improved.