
624 Microwave Engineering
14.4.4.4 HEMTs Fabrication Using IC Technology
HEMTs can be fabricated by using IC technology. Figure 14.32 gives the
sequence for the self-aligned gate procedure in the fabrication of large-scale
integration HEMTs, including the enhancement mode HEMT (E-HEMT) and
depletion mode HEMT (D-HEMT).
1. Ohmic contact formation: In this step, the active region is isolated by
a shallow mesa step (180 nm). This isolation, in general, is achieved
40
35
30
25
20
15
10
5
0
0 1 2 3 4
V
ds
in volts
ds
5 6 7 8
–0.8 V
–0.6 V
–0.4 V
–0.2 V
0.2 V
0.4 V
0.6 V
Vgs =
0 V
FIGURE 14.31
I–V characteristics of HEMT amplier.
contact
(c) (d) ...