The $R_{\text{ON}}-V_{\text{BK}}$ Relationship in $\beta$-Ga2O3 Lateral MESFETs Determined Using Physics-Based TCAD Simulation

$\beta$
-Ga
2
O
3
transistor promises a large breakdown voltage (
$V_{\text{BK}}$
) at a particular on-resistance (
$R_{\text{ON}}$
) that can result in large power figure-of-merit (
$\text{PFoM}=V_{BK}{}^{2}/R_{ON, sp}$
; where
$R_{ON, sp}$
is the area normalized specific
$R_{\text{ON}}$
) for the device [1]. Theoretically calculated PFoM [2] is valid only for vertical transistors, however, is routinely used to compare with the measured PFoM in both lateral and vertical transistors. In particular, transport in lateral transistors has smaller current flow cross-section and is significantly influenced by the 2-D electro-statistics, which is ignored during the measurement and theoretical comparison. In this paper, we present a physics-based TCAD model to determine the
$R_{ON}-V_{BK}$
relationship in lateral MESFETs. The model uses atomistically defined carrier transport parameters and is benchmarked with I-V data measured in similar devices [3]. The model also uses a refined impact ionization model to simulate the intrinsic breakdown in devices, determines the theoretical limit for
$R_{ON}-V_{BK}$
in lateral devices, and hence highlights the importance of considering two-dimensional electrostatics and extrinsic breakdown pathways for understanding the variation of
$V_{BK}$
in lateral devices.