Simulation of Quasi-Vertical E-Mode GaN HEMT on Si Substrate

Gallium Nitride (GaN) power devices are confronting the critical challenge of evolving from lateral to vertical architectures to achieve higher performance. This work presents a quasi-vertical enhancement-mode HEMT (QVE-HEMT) which eliminates the necessity for a complex current blocking layer (CBL). A direct comparison via Technology Computer Aided Design (TCAD) simulations shows that QVE-HEMT, owing to its n--GaN layer, requires a higher drain voltage than the conventional lateral enhancement-mode (CLE-HEMT) device to achieve saturation at the same gate voltage. However, the proposed device achieves a 69.6% higher breakdown voltage (from 246.4 to 418.0 V) than the CLE-HEMT. This improvement is enabled by a unique vertical conduction mechanism, which redistributes the electric field uniformly within the n--GaN drift region to fully utilize GaN’s high critical electric field. This work provides a feasible technical approach for developing high-voltage vertical GaN power devices without complex CBLs.