1.8 mΩ·cm²vertical GaN-based trench metal–oxide–semiconductor field-effect transistors on a free-standing GaN substrate for 1.2-kV-class operation

Abstract

In this paper, we report on 1.2-kV-class vertical GaN-based trench metal–oxide–semiconductor field-effect transistors (MOSFETs) on a free-standing GaN substrate with a low specific on-resistance. A redesigned epitaxial layer structure following our previous work with a regular hexagonal trench gate layout enables us to reduce the specific on-resistance to as low as 1.8 mΩ·cm2 while obtaining a sufficient blocking voltage for 1.2-kV-class operation. Normally-off operation with a threshold voltage of 3.5 V is also demonstrated. To the best of our knowledge, this is the first report on vertical GaN-based MOSFETs with a specific on-resistance of less than 2 mΩ·cm2.

Highly-stable and low-state-density Al2O3/GaN interfaces using epitaxial n-GaN layers grown on free-standing GaN substrates

“…For the trench structure, they used a combination of dry etching and subsequent wet etching with tetramethylammonium hydroxide. Recently, Oka et al 6 also reported a trench-type . In these cases, it was expected that the insulated gate on the dry-etched p-GaN surface could realize device operation with an inverted channel.…”

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…Similar devices can be realized with all-AlGaN or Ga 2 O 3 , with appropriate current blocking techniques, to access higher operating voltages. [217][218][219][220] However, the CAVET suffers from its own problems; for example, it requires a number of etch-and-regrowth steps which to date have resulted in buried pn junctions with excessive leakage current, due to traps introduced at the etched surfaces. Nonetheless, normally-off devices may be easier to realize in a CAVET than in a vertical JFET, again due to the precise doping and layer thickness control afforded by epitaxy as opposed to lithography and implantation.…”

Hydride-vapor-phase epitaxial growth of highly pure GaN layers with smooth as-grown surfaces on freestanding GaN substrates

“…4,5,[27][28][29] Among the various methods for the growth of freestanding GaN substrates, hydride-vaporphase epitaxy (HVPE) is the most well established, and wafers with diameters of 2-in. or more have been prepared and used in the mass production of optoelectronic devices.…”