Body Potential Control via p-Type Contact Resistance and Its Influence on Switching Characteristics of 4H-SiC MOSFETs

Influence of the p-type contact resistance to the p-body region (
$\rho _{\text {body}}$
) on the switching characteristics of 4H-silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) has been investigated. Comparative measurements of the devices with different
$\rho _{\text {body}}$
have experimentally verified an impact of a high
$\rho _{\text {body}}$
on increasing the switching loss. Moreover, simulation analysis has revealed that a high
$\rho _{\text {body}}$
increases the fluctuation in the p-body potential during the switching process, and it leads to a decreased rate of change of the drain–source voltage (
$dV_{\text {ds}}$
/
dt
), thereby increasing the switching loss. The decreased
$dV_{\text {ds}} /$

dt
is attributed to a decrease in the discharging and charging current of the feedback capacitance during the turn-on and turn-off periods, respectively, owing to a high fluctuating p-body potential, which has been clarified by focusing the deviation in the threshold voltage due to the body bias effect and in the gate current through the capacitance between the p-body region and the gate electrode. Furthermore, at a high switching speed, a substantial increase in the calculated turn-on and turn-off loss owing to a high
$\rho _{\text {body}}$
of
$4\times10$
⁻³

$\Omega \cdot $
cm
²
approximates 20% and 50%, respectively. The findings highlight the necessity of precisely controlling
$\rho _{\text {body}}$
to ensure a desirable switching loss of 4H-SiC MOSFETs, especially at a high switching speed.