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

Abstract

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.