Epitaxial Optimization of 130-nm Gate-Length InGaAs/InAlAs/InP HEMTs for High-Frequency Applications

In this paper, the influence of epitaxial-layer design on high-frequency properties of 130-nm gate-length InGaAs/ InAlAs/InP high-electron-mobility transistors (InP HEMTs) has been investigated. The In channel content ([In]: 53%, 70%, and 80%), the J-doping concentration (delta: 3, 5, and 7times10
¹²
cm
^-2
), and the Schottky-layer thickness (d
_SL
: 9,11, and 13 nm) have been varied. The maximum frequency of oscillation f
_max
, the cutoff frequency f
_T
, the drain-to-source current JDS, and the transconductance g
_m
have been analyzed for InP HEMTs. All devices exhibited an increase in I
_DS
with increasing [In], delta, and d
_SL
. An increase in f
_max
, f
_T
, and g
_m
were observed with increasing [In]. When changing [In] from 53% to 80%, f
_T
and f
_max
improved by 14% and 21%, respectively. For the delta parameter, an increase in f
_T
and g
_m
. was found. However, f
_max
was drastically reduced for the highest delta. This is suggested to be due to the formation of a parasitic conduction channel located at the doping plane in the HEMT structure for delta > 6.3 times 10
¹²
cm
^-2
. For the d
_SL
parameter, an optimum with respect to f
_max
, f
_T
, and g
_m
. was observed. The optimized HEMT exhibited an extrinsic f
_T
and f
_max
of 250 and 300 GHz, respectively.