Normally-Off GaN-on-Si MISFET Using PECVD SiON Gate Dielectric

We have developed a silicon oxynitride (SiON) deposition process using a plasma-enhanced chemical vapor deposition system for the gate dielectric of GaN-on-Si metal-insulator-semiconductor field-effect transistors (MISFETs). The optimized SiON film had a relative dielectric constant of 5.3 and a breakdown field of 12 MV/cm. A normally-off GaN-on-Si MISFET fabricated with a 33-nm SiON gate dielectric exhibited a threshold voltage of ~2 V, an ON-resistance of 7.85 mQ · cm
²
, and a breakdown voltage of ~640 V at the OFF-state current density of 1 μA/mm. The extracted interface trap density was 1 × 10
¹²
cm
^-2
· eV
^-1
at E
_c
- E
_t
= 0.442 eV, which resulted in negligible hysteresis and excellent dynamic characteristics.