Study On Ohmic Contact Of SiC SBD

Silicon Carbide(SiC) is the most promising materials for high-power and high temperature electron devices because it has excellent physical properties such as a wide bandgap, high thermal conductivity, and high saturation electron drift velocity compared with the first and the second generation semiconductor materials.Ohmic contact as a basic process is very important to determine the properties of SiC devices. Ohmic contact is not only affected by the doping level of the substrate and the performance of metal materials, but also affected by the grasp of the process parameters during the alloying treatment. This paper mainly focuses on the effect of the annealing temperature and annealing time on the ohmic contact. The main research contents and results are as follows:(1)In the paper, we choose Ni and Pt as the electrode materials, select n type 4H-SiC as substract, and make the technological process. we research the influence of high temperature alloy annealing on ohmic contact, the main content is research the effect of the annealing temperature and annealing time on the ohmic contact.(2)The transmission line model was used to calculate the specific contact resistvity ρc. The result is that the lowest value of specific contact resistvity is 4.0923×10-6?·cm2 which sample is annealed at 1025℃ for 140 s.(3)The surface profile of the electrode under different alloying was studied using Optical Microscopy(OM), at the same time, X-ray diffraction(XRD) measurement was used to identify the phases and the variety of phase structure formed at the interfaces of electrode material at different annealing temperature and annealing time. The result is that the variety and intensity of the phase transformation in contact interface is changing with temperature. When the annealing temperature is 1025℃, NiSi and C are tested. Finally, the stability of the sample annealed at 1025 ℃ for 140 s is tested by ageing test the result is that its thermal stability is good.