Investigation of normally-OFF AlGaN/GaN MIS-HEMTs with Al2O3/ZrOx/Al2O3 charge trapping layer

In this paper, normally-OFF AlGaN/GaN high electron mobility transistors (MIS-HEMTs) with partially recessed gate and Al
2
O
3
/ZrO
x
/Al
2
O
3
charge trapping layer gate dielectrics (CTL) are studied. The threshold voltage (V
th
) of the proposed CTL-HEMTs is 1.56 V, the sub-threshold slope (S.S) is 90 mV/dec and I
ON
/I
OFF
ratio is 10
⁸
. Moreover, saturation drain current (I
Dmax
) and low on-resistance (R
ON
) of CTL-HEMTs is 732 mA/mm and 7.9 Ω•mm (L
GS
= 3μm). Furthermore, the Bi-direction C-V measurement of the MIS-capacitors was measured to explore the charge trapping behavior. The experimental results prove the potential of ZrO
x
CTL to realize the normally-OFF operation MIS-HEMTs with desired performance.