The impact of a recessed Δ-shaped gate in a vertical CAVET AlGaN/GaN MIS-HEMT for high-power low-loss switching applications

A Δ-shaped gate GaN-based E-mode vertical current-aperture vertical electron transistor (CAVET) device with a boron-doped current block layer (B-CBL) on an n+ GaN substrate is proposed, designed, and demonstrated herein. Enhancement-mode (E-mode) operation is achieved in the proposed device by introducing a 1-μm-thick p-GaN CBL layer into the recessed Δ-shaped gate of the metal–insulator–semiconductor (MIS) high-electron-mobility transistor (HEMT) structure. The device exhibits a threshold voltage of 6.76 V, a drain current saturation of Ids,sat = 3.44 kA/cm2, a transconductance of gm = 783.42 S/cm2, and an ON/OFF current ratio > 1010 A/ cm2. The breakdown voltage in the OFF-state (VBR,OFF) shows a maximum of 1590 V and a minimum of 1513 V for a CBL layer thickness (tB-CBL) of 0.2 and 1 µm at a gate bias of 0 V. The lowest ON-state resistance (RON) achieved is 1.24 Ω cm2, accompanied by a low gate current of Ig,L < 10–9 and a drain leakage current of Id,L < 10–8 A/mm. The device exhibits high-frequency performance with peak ft and fmax values of 5.12 GHz and 36.8 GHz, respectively, as measured from two-port Y parameters with an Si3N4 thickness (tSi3N4) of 40 nm and a recessed penetration depth (tpenetration) of 0.2 µm at Vds = 10 V. Finally, the performance of the vertical CAVET AlGaN/GaN MIS-HEMT power switching device with a boron-doped GaN CBL is analyzed using an ultralow-loss boost converter circuit. The results of the analysis of the demonstrated device indicate that it is a suitable candidate for use in high-power low-loss switching applications.