Demonstration of GaN-channel high electron mobility transistors with regrown InAs/GaAs source and drain

Abstract

We demonstrated the crystal growth of group-III arsenides (III-As) on GaN via an arsenidation layer and GaN-channel electron mobility transistors (HEMTs) with a regrowth InAs/GaAs source and drain (S/D) region. By annealing under an AsH3 atmosphere, the surface of a GaN (0001) template is arsenided. We grew ⟨111⟩ oriented InAs and GaAs on arsenided GaN. Silicon-doped n-type InAs with a carrier mobility of over 1500 cm2/V s and a carrier concentration of over 1 × 1019 cm−3 was successfully obtained. The fabrication process and direct-current characteristics of GaN-channel HEMTs with the regrown Si-doped InAs/GaAs S/D region were demonstrated for the first time. A maximum transconductance estimated from transfer characteristics was as high as ∼195 mS/mm for the HEMT with a gate length of 2 μm without passivation, which is comparable to those for the HEMT without any S/D regrowth. The impact of the InAs/GaAs S/D region on the on-resistance of the fabricated HEMTs was estimated to be ∼0.9 Ω mm, which can be reduced by optimizing the device structures and process conditions. These results indicate that the process of GaN arsenidation and III-As regrowth can be used without any device performance degradation. Therefore, further lowering the ohmic contact resistivity and on-resistance of GaN-channel HEMTs is possible by maturing the manufacturing-process technology of III-As-contained GaN-channel HEMTs.