High-Performance Normally-OFF AlGaN/GaN Fin-MISHEMT on Silicon With Low Work Function Metal-Source Contact Ledge

We demonstrate a high-performance normally -OFF AlGaN/GaN fin metal-insulator-semiconductor high electron mobility transistor (fin-MISHEMT) on silicon with a low work function metal-source contact ledge (LWFM-SCL). In order to realize the normally-OFF operation, an optimized gate-recessed fin structure is used. The fin structure inherently containing a gate-connected field plate (FP) design improves the breakdown voltage (V
_BD
). Moreover, the LWFM-SCL can improve the device overall ON-resistance (R
_ON
) by lowering the gate-source access resistance (Ra). The proposed device with a gate-drain length (L
_GD
) of 7 μm exhibits superior characteristics such as a threshold voltage (V
_TH
) of +1.2 V, maximum drain current (I
_D,
max
) of 825 mA/mm, ON-state/OFF-state current (I
_ON
/I
_OFF
) ratio of 10
⁹
-10
¹⁰
, subthreshold swing (SS) of 76 mV/decade, V
_BD
of 810 V, and specific R
_ON
(R
_on,
sp
) of 0.63 mΩ·cm
²
. It also possesses excellent V
_TH
hysteresis, temperature stability, and dynamic R
_ON
characteristics. These results suggest that the proposed device is very suitable for high power switching applications.