Preliminary Demonstration of Diamond-GaN pn Diodes via Grafting

TL;DR

This paper demonstrates a novel diamond-GaN heterojunction pn diode fabricated via grafting, showing promising electrical characteristics and providing insights for future optimization of ultrawide bandgap semiconductor devices.

Contribution

It introduces a new method to create diamond-GaN pn diodes through grafting, overcoming lattice mismatch issues in heterojunction fabrication.

Findings

Diodes exhibit an ideality factor of 1.55.

Rectification ratio exceeds 10,000.

Structural analysis guides future device optimization.

Abstract

Ultrawide bandgap (UWBG) semiconductors exhibit exceptional electrical and thermal properties, offering strong potential for high power and high frequency electronics. However, efficient doping in UWBG materials is typically limited to either n type or p type, constraining their application to unipolar devices. The realization of pn junctions through heterogeneous integration of complementary UWBG or WBG semiconductors is hindered by lattice mismatch and thermal expansion differences. Here, we report the preliminary demonstration of diamond GaN heterojunction pn diodes fabricated via grafting. A single crystalline p plus diamond nanomembrane was integrated onto an epitaxially grown c plane n plus GaN substrate with an ultrathin ALD Al2O3 interlayer. The resulting diodes exhibit an ideality factor of 1.55 and a rectification ratio of over 1e4. Structural and interfacial properties were examined by AFM, XRD, Raman, and STEM, providing critical insights to guide further optimization of diamond GaN pn heterojunction devices.