Integrable Quasivertical GaN U-Shaped Trench-Gate Metal-Oxide-Semiconductor Field-Effect Transistors for Power and Optoelectronic Integrated Circuits

摘要

Integrable, hexagonal-cell, high-voltage, quasivertical GaN power U-shaped trench-gate metal-oxide-semiconductor field-effect transistors (UMOSFETs) fabricated in the n+/p-+ GaN epilayers on sapphire substrates are experimentally demonstrated for the first time. Hexagonal cells, with pitch ranging from 11 to 20 μm, are used to obtain identicalm-plane sidewalls for gate and drain trenches. Metallization compatible with light-emitting diode (LED) optoelectronic integration is used. The dependence of device performance on different parameters is systematically studied and analyzed. The lowest Ron,sp of 23mΩ cm~2 and highest drain saturation current of 295 A cm~(-2) are obtained by measuring an 11 μmcell-pitch UMOSFET. The breakdown voltage of an open-cell design variation (208 V) is higher than that of a closed-cell design variation (89 V), whereas the closed-cell design exhibits a lower off-state leakage current of 1.4 × 10~(-5) A cm~(-2). A hexagonal-cell specific on-state resistance Rcell,sp of 8.5mΩ cm2 and buried nþ layer sheet resistance R_(BL,□) of 223 Ω□~(-1) are extracted by applying a 2D resistance network model to UMOSFETs of varying sizes.