First experimental demonstration and analysis of electrical transport characteristics of a GaN-based HEMT with a relaxed InGaN channel

Abstract

In this paper, we demonstrate the first GaN/InGaN high electron mobility transistor with a partially relaxed InGaN channel, realized by utilizing a porous GaN buffer obtained by the selective and controlled electrochemical etch of GaN. According to reciprocal space map analysis, ∼70% of InGaN relaxation relative to GaN was achieved by this process. With the transfer length method and extracted charge profile, the relaxed InGaN channel demonstrates ∼9.6% two-dimensional electron gas mobility enhancement with respect to the strained InGaN channel which is consistent with a reduced effective mass predicted by theoretical analysis based on Vegard’s law. On comparing the output characteristics of devices with relaxed and strained InGaN channel, the relaxed channel devices show a 10% improvement of on-resistance while maintaining similar saturation current. A non-uniform charge distribution was found in the relaxed InGaN channel, which can be attributed to the strain relaxation fabrication process.