Influence of Graded AlGaN sub-channel over the DC and Breakdown characteristics of a T-gated AlGaN/GaN/AlInN MOS-HEMT.

The impact of graded Al 0. 05 Ga 0. 95 N sub-channel over the DC characteristics of AlGaN/GaN/AlInN Metal Oxide Semiconductor-High Electron Mobility Transistor (MOS-HEMT) has been investigated here. By placing a field plate over the gate region and forming a T-gated structure, the breakdown characteristics are examined using Sentaurus Technology Computer-Aided Design (TCAD) simulation tool. An analytical study is carried out into the evaluation of various device parameters like drain current, transconductance and threshold voltage. RF parameters like cut-off frequency and gain has also been examined. Various physical models such as hydrodynamic, thermodynamic, piezoelectric polarization, impact ionization models are considered. HfO 2 as an oxide layer directly influences the charge confinement near the Two-Dimensional Electron Gas (2DEG), thereby causing a positive shift in the threshold voltage of the device. T-gated formation of the gate helped in enhancing the breakdown voltage of the device to nearly 750 V. A maximum current drive of 1.79 A/mm mm was obtained for the proposed device, nearly 24% improvement from the conventional Composite-channel (CC) HEMT. The current outcomes and the produced frequency characteristics determines the linearity enhancement occurred in the device, caused due to the graded AlGaN sub-channel below the GaN channel layer. The trade-off between specific on-resistance and breakdown voltage is well preserved by employing a T-gated structure with low normal gate length. The outcomes prove the device to be a prime contender for high power switching as well as large signal applications. • The impact of graded AlGaN sub-channel over the DC characteristics of AlGaN/GaN/AlInN MOS-HEMT has been investigated here. • HfO 2 dielectric directly influences the charge confinement near 2DEG, causing a positive shift in the threshold voltage. • T-gated formation of the gate helped in enhancing the breakdown voltage of the device to nearly 750 V. • A 24% enhancement in current drive is observed when the device is brought in comparison with a conventional CC HEMT. [ABSTRACT FROM AUTHOR]