Normally-off AlGaN/AlN/GaN HEMT with a composite recessed gate. (January 2022)

• Record Type: Journal Article
• Authors: Li, Jialin; Yin, Yian; Zeng, Ni; Liao, Fengbo; Lian, Mengxiao; Zhang, Xichen; Zhang, Keming; Li, Jingbo
• Is Part Of: Superlattices and microstructures. Volume 161(2022)
• Publication Date: 2022-01
• Subjects: Normally-off HEMT -- High threshold voltage -- Composite recessed gate -- High saturation current; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2021.107064
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: As we all know, the normally-off HEMT is very important to the safety of power electronic systems. To increase the threshold voltage of the device, this article proposes to cover Al2 O3 on the recessed P-GaN to form the recessed p-GaN HEMT covered with Al2 O3 . Through simulation calculation, covering Al2 O3 on P-GaN can effectively increase the threshold voltage, but the saturation current and transconductance will be severely reduced. Therefore, this article optimizes the structure and proposes a composite recessed-gate HEMT for the first time. It can obtain high saturation current and high transconductance while maintaining a high threshold voltage. Compared with the recessed p-GaN HEMT covered with Al2 O3, the transconductance and saturation current of the composite recessed-gate HEMT are increased by 13.14% and 121.33%, respectively, while the threshold voltage is only reduced by 4.44% (4.3 V). In addition, the gate dielectric has a greater impact on device performance. Therefore, this paper analyzes the influence of the thickness of the Al2 O3 layer on the device through theoretical calculations and obtains the optimal value of the thickness. (T1 = 18.3 nm, Vth = 4.5 V, Isat = 456 mA/mm). The results show that the composite recessed gate has broad application prospects in the next generation of normally-off power device applications. Highlights: Through structural optimization, a composite recessed-gate HEMT is proposed and the device performance is analyzed. The composite recessed gate HEMT can achieve high threshold voltage, high saturation current and high transconductance. The influence of the thickness of the Al2 O3 gate dielectric on the composite recessed-gate HEMT is studied. Through comparative analysis, the optimal thickness of the gate dielectric is 18.3 nm.