Analysis of InGaN Back-Barrier on Linearity and RF Performance in a Graded-Channel HEMT

Abstract

The linearity and radio frequency (RF) performance of a proposed graded-channel HEMT incorporating an InGaN back-barrier layer is investigated by an Atlas simulator. A W-like shape conduction band energy is formed between the top barrier layer and the buffer layer in the proposed architecture. The direct current and the derivatives of transconductance characteristics are analyzed with an In mole fraction from 0 to 0.07. To further effectively evaluate the device linearity, the linearity figures of merit including VIP2, VIP3, IIP3, and 1-dB compression point are compared between the graded-channel HEMTs with and without an InGaN back-barrier layer. The results indicate that the proposed device shows merit in these parameters, and this is mainly a consequence of the special conduction band shape. Additionally, the RF characteristics are calculated for exploring the high-frequency applications in the proposed device. The flatter transconductance characteristic gives rise to higher linearity but also slightly reduces the maximum fT and fmax in the InGaN back-barrier HEMT structures; thus, application-specific trade-offs may need to be considered. The proposed HEMT architecture may be a promising candidate for high-linearity circuit applications.