Interface Charge Effects on 2-D Electron Gas in Vertical-Scaled Ultrathin-Barrier AlGaN/GaN Heterostructure
Sen Huang, Xinhua Wang, Xinyu Liu, Yuchen Li, Jie Fan, Haibo Yin, Wei Ke, Yingkui Zheng, Qian Sun, Bo Shen
Abstract
The combination of ultrathin-barrier (UTB) AlGaN (<; 6 nm)/GaN heterostructure and a charge-modulated SiNx grown by low-pressure chemical vapor deposition (LPCVD) is a promising technique for development of GaN-based millimeter-wave power amplifiers and recessfree enhancement-mode (E-mode) power switches. The LPCVD-SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> passivation is capable of inducing high density of positive charges at the SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> /(Al)GaN interface (~3.50 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ), ensuring efficient recovery of 2-D electron gas (2-DEG) density that is comparable with conventional AlGaN/GaN heterostructure. Temperature-dependent Hall measurements and scattering mechanism simulations confirm the positive interfacial charges as well as interface states with density below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> and exert weak remote coulombic scattering of 2-DEG in metal-insulator- semiconductor heterojunction field-effect transistors (MIS-HFETs), which warrants a low ON-resistance of UTBAlGaN/GaN-based devices. UTB-AlGaN (<; 6 nm)/GaN heterostructure with LPCVD-SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> passivation is a compelling technology platform for fabrication of high-frequency power amplifiers and high-efficiency E-mode power switches.