Abstract
In this study, we proposed a rectifying drain electrode that was embedded in a p-GaN gate AlGaN/GaN heterojunction field-effect transistor to achieve the unidirectional switching characteristics, without the need for a separate reverse blocking device or an additional process step. The rectifying drain electrode was implemented while using an embedded p-GaN gating electrode that was placed in front of the ohmic drain electrode. The embedded p-GaN gating electrode and the ohmic drain electrode are electrically shorted to each other. The concept was validated by technology computer aided design (TCAD) simulation along with an equivalent circuit, and the proposed device was demonstrated experimentally. The fabricated device exhibited the unidirectional characteristics successfully, with a threshold voltage of ~2 V, a maximum current density of ~100 mA/mm, and a forward drain turn-on voltage of ~2 V.
Highlights
AlGaN/GaN heterojunction field-effect transistors (HFETs) have been extensively studied for high-efficiency power switching and high-frequency applications owing to their properties, such as wide energy bandgap, high critical electric field, and two-dimensional electron gas (2DEG) channels with high electron mobility and electron density [1,2,3,4,5,6,7]
A widely adopted device structure for the normally-off mode is a p-GaN gate AlGaN/GaN HFET, where the gate region has a p-GaN layer to deplete the area underneath the AlGaN/GaN channel [4,8,9,10,11,12,13]
We proposed a unidirectional switching device that is based on a normally-off p-GaN gate AlGaN/GaN HFET in which a drain electrode consisted of a rectifying gating electrode and an ohmic electrode
Summary
AlGaN/GaN heterojunction field-effect transistors (HFETs) have been extensively studied for high-efficiency power switching and high-frequency applications owing to their properties, such as wide energy bandgap, high critical electric field, and two-dimensional electron gas (2DEG) channels with high electron mobility and electron density [1,2,3,4,5,6,7]. A widely adopted device structure for the normally-off mode is a p-GaN gate AlGaN/GaN HFET, where the gate region has a p-GaN layer to deplete the area underneath the AlGaN/GaN channel [4,8,9,10,11,12,13]. Such device types have been successfully commercialized and they are currently used in various power modules for different electronic devices, such as fast chargers, switching mode power supplies, and lighting drivers. A reverse blocking device or circuit must be added to the switching device to achieve unidirectional characteristics, which enlarges the chip size and increases the manufacturing cost. The proposed device requires no separate blocking device or additional manufacturing costs
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