MBE-Regrowth Ohmics in AlN/GaN HEMTs with the Rc of 0.09 Ω·mm

This article reports the regrowth ohmic technique in AlN/GaN high electron mobility transistors (HEMTs) on Silicon substrate to optimize the ohmic contact resistance
$(Rc)$
and get the certain control for source/drain spacing
$(L_{SD})$
. According to transmission line modes (TLMs), the 0.09
$\Omega$
. mm
$Rc$
and the 384.3
$\Omega/\text{sq}$
sheet resistance
$(R_{ac,c})$
were gained. Compared to the alloy ohmic process, the regrowth ohmic process made Rc smaller and temperature reliability better. In this paper, we demonstrated AlN/GaN Fin-HEMTs with 2
$\mu \mathrm{m}$
-length L
SD
and a 0.1
$\mu \mathrm{m}$
-length
$L_{G}$
, According to transfer characteristics, the maximum drain current was 2002 mA/mm and transconductance was 555 mS/mm. By microwave small-signal and Load-pull measurement, the
$f_{T}/f_{max}$
of 43/71 GHz, the PAE of 52.65%, the
$P_{out}$
of 0.671 W/mm were achieved, which provided a promising solution for high-performance operation of GaN HEMTs on Si substrate in radio frequency applications.