O3-sourced atomic layer deposition of high quality Al2O3 gate dielectric for normally-off GaN metal-insulator-semiconductor high-electron-mobility transistors

Abstract

High quality Al2O3 film grown by atomic layer deposition (ALD), with ozone (O3) as oxygen source, is demonstrated for fabrication of normally-off AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Significant suppression of Al–O–H and Al–Al bonds in ALD-Al2O3 has been realized by substituting conventional H2O source with O3. A high dielectric breakdown E-field of 8.5 MV/cm and good TDDB behavior are achieved in a gate dielectric stack consisting of 13-nm O3-Al2O3 and 2-nm H2O-Al2O3 interfacial layer on recessed GaN. By using this 15-nm gate dielectric and a high-temperature gate-recess technique, the density of positive bulk/interface charges in normally-off AlGaN/GaN MIS-HEMTs is remarkably suppressed to as low as 0.9 × 1012 cm−2, contributing to the realization of normally-off operation with a high threshold voltage of +1.6 V and a low specific ON-resistance RON,sp of 0.49 mΩ cm2.

Forward Current Transport Properties of AlGaN/GaN Schottky Diodes Prepared by Atomic Layer Deposition

“…In atomic layer deposition (ALD), Al 2 O 3 , Al-Al and Al-O-H bonds have been that the AlInN/GaN Schottky diode has a higher Schottky barrier but a larger reverse leakage current than an AlGaN/GaN Schottky diode, which was attributed to higher defect density and higher tunneling current [11]. In atomic layer deposition (ALD), Al2O3, Al-Al and Al-O-H bonds have been suppressed significantly by replacing the conventional H2O source with O3 and the density of positive bulk/interface charges was reduced to as low as 9 × 10 11 cm −2 [12].…”

Device physics towards high performance GaN-based power electronics

“…该技术通常采用Cl基等离子体(如 应被削弱, 说明高温刻蚀能降低等离子体对AlGaN势 垒层乃至2DEG输运沟道的缺陷损伤 [38] . 除了高温刻蚀, 研究者同时研发出更低损伤的数 字式刻蚀方法 [39,40] [43] .…”

“…GaN缓冲层上(AlGaN势垒层过刻蚀)制备的MIS二极 管I-V特性. 栅介质显示出良好的绝缘性能, 在偏压低 于+10 V时漏电保持在2´10 -7 A/cm 2 以下, 介质硬击穿 [43] . 尽管如此, 由于O3具有较强的氧…”

“…Ni/Al2O3/GaN MIS二极管的I-V特性[43] -V characterizations of large-area Ni/Al2O3/AlGaN/GaN MIS diodes with the AlGaN barrier over recessed[43].…”

Analysis of threshold voltage instability in AlGaN/GaN MISHEMTs by forward gate voltage stress pulses

“…Thus, the insulating gate module allows the MISHEMT to be operated into a potentially higher gate‐overdrive, when compared to conventional HEMT devices with Schottky gate. In particular, SiO 2 or high‐ κ materials, such as SiN , Al 2 O 3 and HfO 2 have been widely studied as promising gate dielectrics for future MISHEMTs. However, in terms of reliability aspects, trapping phenomena and control of the threshold voltage ( V th ) are one of the major challenges to be understood and optimised.…”