Device Design Implications on R_ON×Q_OSS FOM in p-GaN Power HEMTs: A Simulation Study

In this paper, we analyze by means of numerical simulations the device design implications on the R_ON×Q_OSS Figure of Merit (FOM) in p-GaN power HEMTs to be employed in soft-switching converters. During switching, p-GaN power HEMTs experience dynamic R_ON increase but also dynamic Q_OSS reduction, effectively establishing a trade-off between the two device parameters. This trade-off stems from the physical mechanism of hole redistribution within the C-doped buffer. Device design choices such as field plate length, channel and buffer thickness as well as C-doping concentration influence both parameters; however, the relative variation of the two parameters is not necessarily symmetric. Simulations are therefore carried out to identify the best device design choices depending on the target trade-off between R_ON and Q_OSS.