Silicon carbide power diode with three-junction terminal expansion structure and preparation method of silicon carbide power diode

The invention discloses a silicon carbide power diode with a three-junction terminal expansion structure and a preparation method of the silicon carbide power diode. The main structure of the device is a cylindrical structure, and the device sequentially comprises an N + type SiC substrate layer, an N-type SiC drift layer and a P + type SiC layer from bottom to top. The three JTE structures of the device surround the P + type SiC layer and expand from inside to outside in a concentric circle shape, P type impurity doping is adopted, but the doping sizes and uniformity are different; and the upper electrode and the lower electrode are respectively led out from the P + type SiC layer and the N + type SiC substrate layer. The gradient impurity doping of the G-JTE2 layer is realized by introducing graphene as an ion implantation technology of a mask layer and a vertical displacement control technology of the mask layer. The SiC gradient impurity doping process and the JTE structure of the device are creatively im