A Novel Enhancement-Mode Gallium Nitride p-Channel Metal Insulator Semiconductor Field-Effect Transistor with a Buried Back Gate for Gallium Nitride Single-Chip Complementary Logic Circuits

Abstract

In this work, a novel enhancement-mode GaN p-MISFET with a buried back gate (BBG) is proposed to improve the gate-to-channel modulation capability of a high drain current. By using the p-GaN/AlN/AlGaN/AlN double heterostructure, the buried 2DEG channel is tailored and connected to the top metal gate, which acts as a local back gate. Benefiting from the dual-gate structure (i.e., top metal gate and 2DEG BBG), the drain current of the p-MISFET is significantly improved from −2.1 (in the conv. device) to −9.1 mA/mm (in the BBG device). Moreover, the dual-gate design also bodes well for the gate to p-channel control; the subthreshold slope (SS) is substantially reduced from 148 to ~60 mV/dec, and such a low SS can be sustained for more than 3 decades. The back gate effect and the inherent hole compensation mechanism of the dual-gate structure are thoroughly studied by TCAD simulation, revealing their profound impact on enhancing the subthreshold and on-state characteristics in the BBG p-MISFET. Furthermore, the decent device performance of the proposed BBG p-MISFET is projected to the complementary logic inverters by mixed-mode simulation, showcasing excellent voltage transfer characteristics (VTCs) and dynamic switching behavior. The proposed BBG p-MISFET is promising for developing GaN-on-Si monolithically integrated complementary logic and power devices for high efficiency and compact GaN power IC.