AlGaN/GaN MOS-HEMT Device Fabricated Using a High Quality PECVD Passivation Process

In this letter, an AlGaN/GaN MOS-HEMT was demonstrated using a 5-nm-thick SiO
_x
dielectric layer deposited by plasma enhanced chemical vapor deposition (PECVD) as a gate insulator. The fabricated device exhibits a maximum I
_DS
current of 570 mA/mm at V
_GS
=+ 3 V, an ON-state resistance (R
_bioscon
) of 7.3 · mm, a maximum transconductance peak of 180 mS/mm, and a gate leakage current below 1 nA/mm at a gate voltage of +/- 3 V. Moreover, a very low pinchoff voltage (V
_p
) shift was observed during the I
_DS
-V
_GS
hysteresismeasurements giving an estimated interface state density (D
_it
) as low as 3.9 × 10
¹¹
cm
^-2
eV
^-1
. These results demonstrate the high quality of the SiO
_x
/AlGaN interface and the efficiency of the passivation process. To the best of our knowledge, this is the lowest reported D
_it
on an AlGaN/GaN MOS-HEMT device using a PECVD deposition technique.