An Advanced Epitaxial Strategy Enabling Vertical GaN Devices on Silicon Wafers

TL;DR

This paper introduces a sputtering-based method to grow high-quality GaN films on silicon wafers with low resistance and high stability, enabling better vertical GaN devices for power electronics and micro-LEDs.

Contribution

A universal sputtering technique with in-situ silicide template formation that improves epitaxial quality and reduces resistance in GaN-on-silicon structures.

Findings

Achieved low vertical resistance and ohmic contact in GaN films on Si(111).

Demonstrated versatility across 25 metallic species for template formation.

Enabled high-quality MOCVD overgrowth on the templates.

Abstract

While vertical GaN-on-silicon architectures promise a transformative leap in cost-effective power electronics and high-resolution micro-LEDs, their deployment remains bottlenecked by the high electrical resistance of conventional epitaxial buffer layers. Here, a universal and straightforward sputtering-based strategy is presented to realize high quality GaN epitaxial films on Si(111) substrates characterized by exceptionally low vertical resistance, ohmic behavior, and robust thermal stability. This technique centers on the in-situ formation of a sub nanometer (0.5 nm) silicide-based template via rapid thermal annealing method demonstrating unprecedented versatility across 25 different metallic species. Scanning transmission electron microscopy (STEM) reveals that a unique amorphous like interlayer (AL-IL) effectively accommodates lattice mismatch and relaxes epitaxial strain. These AL-IL templates further serve as high performance platforms for metalorganic chemical vapor deposition (MOCVD) overgrowth, successfully bridging the gap between scalable, low-cost fabrication and device-grade vertical performance.