Patent ID: 11948983
Assignee: XIDIAN UNIVERSITY
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 6:
7. The SiC ohmic contact preparation method according to claim 6, wherein the transferring the graphene onto the Si-face of the SiC substrate to prepare the graphene/SiC structure comprises:
selecting a copper foil and using a CVD equipment to grow the graphene on the copper foil, and process conditions sequentially including: introducing 1000 sccm of argon gas into the CVD equipment and heating up to 1000° C. at 200° C./min; shutting down the argon gas and introducing 1000 sccm of hydrogen gas for 5 min; gradually changing the introduced gas to be 960 sccm of argon gas and 40 sccm of hydrogen gas and introducing 10 sccm of methane gas for 10 min; and shutting down a source of the methane gas, cooling down to 300° C. at 200° C./min, then cooling down to 150° C. naturally, closing all gas sources, and vacuuming to 0.1 mbar;
spin-coating a polymethyl methacrylate (PMMA) solution onto a surface of the graphene, removing the copper foil by a corrosive solution to form a PMMA/graphene composite structure, and floating the PMMA/graphene composite structure on the corrosive solution, and process conditions including: a spin-coating speed is 3000 revolutions per minute (rpm), a spin-coating time is 1 min, the corrosive solution is a ferric chloride solution of 0.5 mole per liter (mol/L), and a corrosion time is 4 h;
using the SiC substrate to transfer the PMMA/graphene composite structure from the corrosive solution to thereby form a PMMA/graphene/SiC composite structure and then cleaning the PMMA/graphene/SiC composite structure, and process conditions sequentially including: tilting the SiC substrate at an angle by a tweezer, placing the SiC substrate directly below the PMMA/graphene composite structure and lifting the SiC substrate; placing the PMMA/graphene/SiC composite structure into a solution of H2O:H2O2:HCl=20:1:1 for 30 min, then placing into another solution of H2O:H2O2:NH4OH=5:1:1 for 30 min; and subsequently repeatedly cleaning by deionized water; and drying water between the graphene and the SiC substrate; and
removing the PMMA and annealing to form the graphene/SiC structure, and process conditions sequentially including: removing the PMMA by hot acetone, washing with ethanol solution, and cleaning repeatedly with deionized water; and vacuum annealing, concretely in a mixed atmosphere of hydrogen and argon, annealing at 200° C.˜400° C. for 3 h.