Design of kV-Class and Low R_ON E-Mode -Ga₂O₃ Current Aperture Vertical Transistors With Delta-Doped -(Al_xGa_1-x)2O₃/Ga ₂O₃ Heterostructure

This work demonstrated a comprehensive design and modeling of enhancement-mode (E-mode) betaphase gallium oxide (ss-Ga2O3) current-aperture vertical electron transistors (CAVETs) using TCAD simulation. A new ss-Ga2O3 CAVET [i.e., high electron mobility transistors (HEMT)-CAVETs] was proposed by introducing delta-doped ss-(AlxGa1-x)(2)O-3/Ga2O3 (x = 0.2) heterostructure into the conventional CAVETs. The HEMT-CAVETs showed significant improvements in electron modulation, ON-state resistance (RON), and leakage due to the confined two-dimensional electron gas (2DEG) channel. The design space of doping, channel length (Lch), and aperture length (Lap) on the device threshold voltages (VTH), RON, breakdown voltage (BV), and OFF-state leakage were systematically investigated. With increasing delta-doping concentration, the HEMT-CAVETs showed smaller RON compared with the conventional CAVETs. The OFF-state leakage from the aperture and the current blocking layers (CBLs) in the ss-Ga2O3 CAVETs was studied for the first time. Larger Lch prevented the OFF-state leakage current from the aperture and increased BV, but it also increased RON due to larger channel resistance. Small Lap could dramatically increase device RON due to the encroachment of the aperture by the depletion regions from the CBLs. The CBL breakdown played a key role in the device BV. The BV of the CBL increased with increasing CBL thickness and acceptor doping concentration, where kV-level BV and high peak electric fields of similar to 8 MV/cm can be obtained with optimized CBLs. These results can serve as a critical reference for the future development of kV-class low RON ss-Ga2O3 CAVETs for high-power, high-voltage, and highfrequency applications.