Design of kV-Class and Low RON E-Mode β-Ga2O3 Current Aperture Vertical Transistors With Delta-Doped β-(AlxGa1−x)2O3/Ga2O3 Heterostructure

This work demonstrated a comprehensive design and modeling of enhancement-mode (E-mode) beta-phase gallium oxide (
$\beta $
-Ga2O3) current-aperture vertical electron transistors (CAVETs) using TCAD simulation. A new
$\beta $
-Ga2O3 CAVET [i.e., high electron mobility transistors (HEMT)-CAVETs] was proposed by introducing delta-doped
$\beta $
-(AlxGa
$_{{1}-{x}}$
)2O3/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 (
${L}_{\text {ch}}$
), and aperture length (
${L}_{\text {ap}}$
) on the device threshold voltages (
${V}_{\text {TH}}$
), 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
$\beta $
-Ga2O3 CAVETs was studied for the first time. Larger
${L}_{\text {ch}}$
prevented the OFF-state leakage current from the aperture and increased BV, but it also increased RON due to larger channel resistance. Small
${L}_{\text {ap}}$
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
${\sim }8$
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
$\beta $
-Ga2O3 CAVETs for high-power, high-voltage, and high-frequency applications.