Research Of Resistance Switching And Photoconductivity Based On ?-CuSCN Micro/Nano Structure

With the development of micro-electronics technology and the limits of miniaturization of the flash memory,the resistive switching random access memory(RRAM)is one of the strong competitors of next generationnonvolatile memory due to its high-speed and high-density storage.At present its working mechanism is not very clear,finding the appropriate resistance materials and demonstrating its definite physical mechanism is important forthe further development of the RRAM.?-CuSCN is a wide bandgap(3.6 eV)semiconductor,with excellent optical,electrical,chemical,thermal and other properties.In this paper,?-CuSCN micro-nano thin films were prepared by electrochemical deposition method.The properties of resistance switching(RS)of CuSCN were studied,and reasonable physical mechanism was given in order to obtain better application in resistive memory.In addition,we further explore its potential in the application of photoelectric detection.The main results are as follows:(1)ITO/CuSCN/ITO resistance memory with sandwich symmetrical structure was fabricated by using ITO as electrode.The device can show negative RS characteristics with symmetrical negative differential resistance behavior(NDR)at a relatively high operation bias.We demonstrate that typical bipolar RS can reversibly be realized at a low operation bias by applying relatively large fixed bias in opposite directions.After applying a large fixed bias,an n-type reversion layer can be formed at the surface connected with the positive electrode and a depletion layer next to the reversion layer due to the polarization-induced aggregation of minority carriers(electrons),and contrarily an accumulation layer without barrier can be formed at the surface connected with the negative electrode due to the aggregation of majority carriers(holes).Afterward,the devices can be set and reset by the filling and emptying of holes in the high barrier reversion and depletion layer at low reverse and forward bias,respectively.The device has a memory window of 10 at a small read voltage of 0.2 V and the change of current at the high and low resistance states is very tiny after about 2 h of stability test.(2)We introduced organic PVDF as the interlayer and fabricated CuSCN/PVDF/ ZnO p-i-n heterostructure type resistive memory based on ITO symmetrical electrode.The device exhibits a typical bipolar resistive switching and can quickly store and erase information.Electron injection or discharge induced by numerous trap caused the quantum tunneling effect between the ZnO conduction band and the CuSCN valence band,and then the nonvolatile storage was fabricated.(3)The photoconductivity based on CuSCN micro-nanostructure device was studied.The device has a strong photoelectric response to UV light near 390 nm and has a certain response to the visible light.We also found the response to light is different in positive and negative bias due to the different barrier height at both ends of the device.