
134 Gallium Nitride (GaN): Physics, Devices, and Technology
Model parameters
MSG
–20dB.decade
Gen-IV
Asymmetric self-aligned-gate
3D n
+
- GaN - 2DEG contact
30
20
10
0
110 100
gains
L
g
= 20 nm
g
m
(mS/mm) 1484
136
574
89
0.03
0.38
0.13
0.18
327
558
g
d
(mS/mm)
C
gs
(fF/mm)
C
gd
(fF/mm)
R
i
(Ω·mm)
R
g
(Ω·mm)
R
s
(Ω·mm)
R
d
(Ω·mm)
f
T.model
(GHz)
f
max.model
(GHz)
L
gs
= 30 nm
L
gd
= 80 nm
V
ds
= 4.0 V
V
gs
= 0.25 V
I
ds
= 0.53 A/mm
U
g
|h21|
2
f
T
= 329 GHz
f
max
= 554 GHz
FIGURE 4.27 Measured and modeled RF gains versus frequency (0.5–65 GHz) for 20-nm
asymmetric self-aligned-gate HEMT with L
gs
= 30 nm and L
gd
= 80 nm. (K. Shinohara et al.,
Scaling of GaN HEMTs and Schottky d