Y. Kwon et al., EXPERIMENTAL AND THEORETICAL CHARACTERISTICS OF HIGH-PERFORMANCE PSEUDOMORPHIC DOUBLE-HETEROJUNCTION INALAS IN0.7GA0.3AS/INALAS HEMTS/, I.E.E.E. transactions on electron devices, 42(6), 1995, pp. 1017-1025
Pseudomorphic double heterojunction (DH) InAlAs/In0.7Ga0.3As/InAlAs HE
MT's with very high cut-off frequencies and current densities have bee
n demonstrated, DC and microwave characteristics of the double heteroj
unction acid single heterojunction (SIF) HEMT's have been compared, Tw
o identical layers except for the dopings have been grown and fabricat
ed using a conventional non-self-aligned process for this purpose, In
order to further enhance the performance level of DH-HEMT's, a sub-0.1
mu m offset Gamma-gate self-aligned process has been used on DH layer
s, A maximum frequency of oscillation (f(max)) of 350 GHz and a curren
t gain cut-off frequency (f(T)) of 180 GHz have been achieved in this
way along with the full channel current of 1.2 A/mm, Theoretical simul
ation using 2-D ensemble Monte Carlo simulation has also been performe
d to optimize the DH layer structure and to study the transport charac
teristics of DH-HEMT's compared with SH counterparts.