Band alignment of grafted diamond/GaN p-n heterojunctions interfaced with ALD Al2O3 and SiNx/Al2O3

TL;DR

This study investigates the band alignment of diamond/GaN heterojunctions with different interfacial layers, revealing how interfacial engineering can tune diode properties for improved device performance.

Contribution

It provides the first detailed analysis of how inserting SiNx modifies the band offsets in diamond/GaN heterostructures using X-ray photoelectron spectroscopy.

Findings

Both structures exhibit type-II band alignment.

The band offsets increase by 0.42 eV with SiNx insertion.

Interfacial electrostatic potential modification explains the offset change.

Abstract

Diamond and gallium nitride are complementary semiconductors for forming p-n junctions because of their respective doping limitations. Understanding the band alignment of grafted diamond/GaN heterojunctions is therefore essential for optimizing diode performance. In this study, the band alignment of diamond/Al2O3/GaN and diamond/Al2O3/SiNx/GaN heterostructures was determined by X-ray photoelectron spectroscopy. Both structures exhibit type-II band alignment, but with different band offsets. The band offsets of the diamond/Al2O3/SiNx/GaN heterojunction are larger by 0.42 eV than those of diamond/Al2O3/GaN. This difference is attributed to a modification of the interfacial electrostatic potential, which may arise from a reduced density of positive fixed charges in the interfacial dielectric near the diamond/Al2O3 interface after insertion of the SiNx layer. These results demonstrate that interfacial-layer engineering provides an effective strategy for tailoring the band alignment of grafted diamond/GaN heterojunctions, offering guidance for the design of p-n diodes with tunable rectifying characteristics.