Impact of Channel Electric Field Profile Evolution on Nanosecond Timescale Cyclic Stress-Induced Dynamic RON Behavior in AlGaN/GaN HEMTs—Part II

In this work, we reveal a correlation between the evolution of the channel electric field profile and dynamic ON resistance (
${\Delta } {R}_{ {\mathrm {ON}}}$
) behavior of AlGaN/GaN HEMTs when subjected to cyclic nanosecond pulse stress on the drain terminal. Two scenarios of field profile evolution were studied: 1) field peak shifting from gate/field plate edge (GE/FP) to drain edge (DE) and 2) field peaking near GE/FP edge but not showing any shift. The devices exhibiting a shift in the electric field peak to DE in response to the cyclic stress showed a unique increase in
${\Delta } {R}_{ {\mathrm {ON}}}$
which was absent in devices that did not show any such field shift. Factors accelerating this field shift to DE, including drain bias, channel current, and stress pulsewidth (PW), were found to accelerate the increase in
${\Delta } {R}_{ {\mathrm {ON}}}$
. Furthermore, the devices exhibiting such an increase in
${\Delta } {R}_{ {\mathrm {ON}}}$
showed a slower recovery of the ON-resistance when compared to devices with field peak only near the GE/FP edge. Physical insights were developed using detailed experimentation and well-calibrated computations, which could capture the observed phenomenon. The developed insights and proposed mechanisms were then experimentally validated by studying the dependence of the
${\Delta } {R}_{ {\mathrm {ON}}}$
behavior on: 1) passivation thickness-induced electric field profile modulation and 2) substrate temperature-induced trapping/detrapping rate modulation.