Analytical model for reverse characteristics of 4H--SiC merged PN--Schottky (MPS) diodes

A new analytical model for reverse characteristics of 4H--SiC merged PN--Schottky diodes (MPS or JBS) is developed. To accurately calculate the reverse characteristics of the 4H--SiC MPS diode, the relationship between the electric field at the Schottky contact and the reverse bias is analytically established by solving the cylindrical Poisson equation after the channel has pinched off. The reverse current density calculated from the Wentzel--Kramers--Brillouin (WKB) theory is verified by comparing it with the experimental result, showing that they are in good agreement with each other. Moreover, the effects of P-region spacing (S) and P-junction depth (X_j) on the characteristics of 4H--SiC MPS are analysed, and are particularly useful for optimizing the design of the high voltage MPS diodes.