Abstract
A gallium nitride (GaN) semiconductor vertical field-effect transistor (VFET) has several attractive advantages such as high power density capability and small device size. Currently, some of the main issues hindering its development include the realization of normally off operation and the improvement of high breakdown voltage (BV) characteristics. In this work, a trenched-gate scheme is employed to realize the normally off VFET. Meanwhile, an additional back current blocking layer (BCBL) is proposed and inserted into the GaN normally off VFET to improve the device performance. The electrical characteristics of the proposed device (called BCBL-VFET) are investigated systematically and the structural parameters are optimized through theoretical calculations and TCAD simulations. We demonstrate that the BCBL-VFET exhibits a normally off operation with a large positive threshold voltage of 3.5 V and an obviously increased BV of 1800 V owing to the uniform electric field distribution achieved around the gate region. However, the device only shows a small degradation of on-resistance (RON). The proposed scheme provides a useful reference for engineers in device fabrication work and will be promising for the applications of power electronics.
Highlights
With the rapid development of the power electronics industry, Si- or GaAs-based devices are approaching their material limit
back current blocking layer (BCBL)-vertical field-effect transistor (VFET) acts as the top current blocking layer (TCBL) to sustain the main bias voltage between the drain andacts source electrodes, which is similar to the case in the
The doping concentration of the main bias voltage between the drain and source electrodes, which is similar to the case in the employed forVFET
Summary
With the rapid development of the power electronics industry, Si- or GaAs-based devices are approaching their material limit. GaN-based lateral high electron mobility transistor (HEMT) devices have been extensively demonstrated and have made great progress in the past few decades [5,6,7,8] These lateral devices still encounter a few issues such as power density limit and output current collapse. The peak electric field is located at the drain-side gate corner of the HEMT surface, which leads to a limiting of the device output characteristics and a serious reliability issue when operated under high voltage [9,10] Another challenge in lateral GaN-based HEMT is how to make the normally off device. Improved BV and RON were achieved after optimizing the thickness, depth, and spatial location of the current blocking layer in the GaN BCBL-VFET
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