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.