
93Gallium Nitride Transistors on Large-Diameter Si(111) Substrate
with 18-nm-thick AlGaN barrier exhibited a I
Dmax
of 830 mA/mm,ag
mmax
of 263 mS/
mm, and a V
th
of −3.75 V. Subsequently, the HEMTs with 5-nm-thick AlGaN bar-
rier exhibited a I
Dmax
of 470 mA/mm, a g
mmax
of 310 mS/mm, and a V
th
of −0.82 V.
The Ni/Al/Ta Schottky gate exhibited a barrier height of 0.88 eV and a reverse gate-
leakage current (−20 V) of 3.8 × 10
−
3 mA/mm.
Figure 3.32 shows the small-signal gain versus frequency for the CMOS-
compatible non-gold metal stack AlGaN/GaN HEMTs with (a) 18-nm-thick AlGaN
300
200
100
0
–6 –4 –2
V
GS
(V)
0
200
400
600
800
m
I
D
(mA/mm)
I
D
(18 nm) ...