Dynamic RON Degradation in AlGaN/GaNMIS-HEMTs With Si3N4 or Si3N4/ZrO2Passivation Layer

The dynamic
${R}_{ \mathrm{\scriptscriptstyle ON}}$
degradation in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with different passivation layers (SiSi3N4 or Si3N4/ZrO2 stack) under off-, semi-on, and ON-state stress have been investigated in this work. Under the OFF-state stress of 40 V, a 20% reduction in the maximum drain current has been observed in devices passivated with Si{3}N{4}, along with a degraded
${R}_{ \mathrm{\scriptscriptstyle ON}}$
that is 1.42 times higher than the initial
${R}_{ \mathrm{\scriptscriptstyle ON}}$
. In contrast, devices passivated with Si3N4 or Si3N4/ZrO2 stack have only shown a 2% reduction, and the
${R}_{ \mathrm{\scriptscriptstyle ON}}$
degradation is only 1.03 times higher than the initial
${R}_{ \mathrm{\scriptscriptstyle ON}}$
. This can be attributed to the different interface states present in the two devices. According to the multifrequency
$\vphantom {_{\int _{\text {a}}}}~{C}$
–
${V}$
curves, the Si3N4/GaN-cap interface trap density is in the range of
$2\times 10^{{13}}$
–
$5.5\times 10^{{13}}$
from
${E}_{C}-{0.47}$
to
${E}_{C}-{0.37}$
eV, and ZrO2/GaN-cap interface trap density is in the range of
$2.7\times 10^{{12}}$
–
$1.2\times 10^{{13}}$
from
${E}_{C}-{0.47}$
to
${E}_{C}-{0.31}$
eV. Under the semi-on state stress, the dynamic
${R}_{ \mathrm{\scriptscriptstyle ON}}$
degradation exhibits a “bell-shaped” behavior in the Si3N4 or Si3N4/ZrO2 stack passivated sample. Arrenhius plots indicate that the sample passivated by Si3N4 has an activation energy of 0.06 eV, while the sample passivated by Si3N4 or Si3N4/ZrO2 stack has an activation energy of 0.16 eV, which means a deeper trap distribution. The
${R}_{ \mathrm{\scriptscriptstyle ON}}$
degradation under semi-on/ ON-state stress in Si3N4 or Si3N4/ZrO2 passivated devices can be attributed to the hot-electron-related injection mechanism. Device designers must consider the trade-off between the high breakdown voltage (BV) and the
${R}_{ \mathrm{\scriptscriptstyle ON}}$
degradation in Si3N4 or Si3N4/ZrO2 passivated devices.