Dynamic Gate Stress-Induced $V_{\text {TH}}$ Shift and Its Impact on Dynamic $R_{\mathrm {ON}}$ in GaN MIS-HEMTs

Very fast transients of
$V_{ {\text {TH}}}$
shift and their impact on
$R_{\mathrm{\scriptscriptstyle ON}}$
under dynamic AC (1 k–1 MHz) positive gate stress in depletion-mode (D-mode) metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) are revealed. We achieve data acquisition within 120 ns right after each stress pulse throughout the entire stress time range from
$10^{ { {-7}}}$
up to
$10^{ { {3}}}$
s, by virtue of a short stress-to-sense delay of
$\sim 100$
ns and high sampling rate up to 50 MSa/s. Despite the considerable
$V_{\mathrm {\mathbf {TH}}}$
shift, its impact on
$R_{\mathrm{\scriptscriptstyle ON}}$
in D-mode MIS-HEMT is modest, if the device is under sufficient gate overdrive. Furthermore,
$V_{\mathrm {\mathbf {TH}}}$
shift and the consequent
$R_{\mathrm{\scriptscriptstyle ON}}$
increase under dynamic stress, which are more relevant to high-frequency switching operation, exhibits frequency dependence within 1 k–1 MHz and is always smaller than that under conventionally used static (constant) stress.