Publication Date

1-1-2026

Document Type

Conference Proceeding

Publication Title

IEEE Workshop on Microelectronics and Electron Devices Wmed

DOI

10.1109/WMED71264.2026.11509678

First Page

5

Last Page

9

Abstract

Superlattice GaN structures are expected to have reduced on-state resistance due to the formation of multiple twodimensional electron gas (2DEG) channels in the access regions. The U-GaN structure, which has one channel in the gate region for normally-off operation, employs regrown Si-doped vertical GaN sidewalls to electrically connect multiple channels in the access regions. In this paper, an access region with thin superlattice layers, which is expected to have less relaxation and dislocations than the thicker one, is studied. Technology Computer-Aided Design (TCAD) simulations confirm the formation of multiple polarization-induced 2DEG channels. It is found that the equivalent access-region sheet resistance remains nearly constant for different numbers of channels, resulting in similar drain currents at linear regime, while enhanced current is only observed in multiple channels in the saturation regime. This is due to strong electrostatic coupling between the layers. A compact model is developed to model the behaviors based on the Massachusetts Institute of Technology (MIT) Virtual Source GaNFET HighVoltage (MVSG-HV) model. To fit the TCAD data, a drain-voltage-dependent threshold-voltage shift needs to be introduced in the access-region transistors due to the nature of the model, in which the access region's effective 'gate voltage' is calculated by the 2DEG sheet resistance. Moreover, it is also found that hole tunneling needs to be turned on in the source/drain Schottky barriers to allow accurate TCAD simulations, likely to avoid isolated holes.

Funding Number

2424859

Funding Sponsor

National Science Foundation

Keywords

Compact model, GaN HEMT, superlattice, TCAD

Comments

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Department

Electrical Engineering

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