Simulation Of In Situ Graphene-SiC Ohmic Contact And Its Electrode Application

With the rapid development of aerospace,smart grid and other advanced equipment industry,the demand for the performance of integrated circuit is also increasing.Due to the wide band gap physical characteristics of SiC material,so it can be easily adapted to high temperature,high power and other working conditions.However,the related technology of SiC is not mature enough,especially the ohmic contact technology.Whether a low specific contact resistivity and high reliability ohmic contact can be formed seriously restricts the performance of SiC devices.Most of the studies on ohmic contact of SiC domestic and overseas focus on the optimization of metal composition and process.The research in the corresponding direction is gradually becoming mature.In order to further reduce the ohmic contact resistance and improve its reliability,a new research direction need to be put forward.Based on literature research,in this paper we proposed the SiC-graphene-Metal ohmic contact structure,and the electrical and thermal properties were studied by simulation,the preparation scheme of high repeatability of SiC-graphene-Metal structure was designed,and the SiC graphene-Metal was applied to optical switch structure,the simulation on compression properties of optical switch and quantum efficiency were analyzed.1.In order to get more intuitive simulation results,we put forward the SiC-graphene-Metal ohmic contact combined with MOSFET structure,using SiC-graphene-Metal structure to replace the MOSFET source leakage,and under the condition of grid voltage consistent,to simulate the MOSFET before and after the replacement,through the change of the saturation drain current analysis ohmic contact performance boost.In this paper,modeling and simulation were carried out according to the number of graphene layers in SiC-Graphene-Metal structure and the different binding modes of graphene with SiC substrate.The simulation results show that,compared with the traditional semi-contact structure,the SiC-graphene-Metal structure effectively reduces the ohmic contact specific resistance,and obtain higher heat dissipation performance.It proves the feasibility of the research direction proposed in this paper.2.Due to the preparation process of SiC-graphene-Metal structure,the graphene layer is very easy to be stained and damaged,which seriously affects the performance of the device.In this paper,a set of preparation process of SiC-graphene-Metal structure was designed.The graphene layer was effectively protected by pre-deposit a layer of Au film on it.The higher pass-rate of the device is guaranteed,and the repeatability of the ohmic contact process is improved.3.In this paper,SiC-Graphene-Metal structure is applied to the photoconductive switch,five kinds of photoconductive switch structures are proposed,and different structures are modeled respectively.Through the simulation of the field intensity distribution and collision ionization integral of the photoconductive switch in dark and transient state,the voltage resistance performance of the switch with different structure is analyzed.Under1000W/cm~2 light intensity,the quantum efficiency of different structures of photoconductive switches was simulated.The simulation results show that,the application of SiC-graphene-Metal structure in the photoconductive switch effectively transfers the highest field strength from the anode surface to the inside of the SiC substrate,which greatly improves the voltage resistance of the switch.Graphene as a transparent electrode shows excellent light absorption characteristics in the simulation.The anode is SiC-Graphene-Metal structure,and the cathode is a photoconductive switch with a circular Metal electrode with an Ag mirror reflection layer,which shows the best performance in terms of voltage resistance and quantum efficiency.The SiC-Graphene-Metal ohmic contact structure was proposed in this paper,which shows excellent electrical,thermal and optical properties according to the simulation results and provides qualitative analysis for our research and simulation basis for subsequent research.A new way for the study of SiC ohmic contact was opened up,which provides a new possibility for further reducing the ohmic contact resistance of SiC and improving the reliability of SiC ohmic contact,also has important practical value for the further development of SiC devices.