Mapping the local spatial charge in defective diamond by means of NV sensors - A "self-diagnostic" concept

TL;DR

This paper demonstrates a novel method using NV centers in diamond to directly map internal electric fields caused by defects, enabling a self-diagnostic approach to understand charge trapping and conduction mechanisms in diamond-based devices.

Contribution

It introduces a new NV-based sensing technique for direct, local electric field mapping in diamond, revealing defect-related charge effects with high spatial resolution.

Findings

NV ensembles enable nanoscale electric field mapping

Defect complexes serve as both sources of space charge and diagnostic tools

The method provides direct insights into conduction mechanisms

Abstract

Electrically-active defects have a significant impact on the performance of electronic devices based on wide band-gap materials such as diamond. This issue is ubiquitous in diamond science and technology, since the presence of charge traps in the active regions of different classes of diamond-based devices (detectors, power diodes, transistors) can significantly affect their performances, due to the formation of space charge, memory effects and the degradation of the electronic response associated with radiation damage. Among the most common defects in diamond, the nitrogen-vacancy (NV) center possesses unique spin properties which enable high-sensitivity field sensing at the nanoscale. Here we demonstrate that NV ensembles can be successfully exploited to perform a direct local mapping of the internal electric field distribution of a graphite-diamond-graphite junction exhibiting electrical properties dominated by trap- and space-charge-related conduction mechanisms. By performing optically-detected magnetic resonance measurements, we performed both punctual readout and spatial mapping of the electric field in the active region at different bias voltages. In this novel "self-diagnostic" approach, defect complexes represent not only the source of detrimental space charge effects, but also a unique tool to directly investigate them, by providing experimental evidences on the conduction mechanisms that in previous studies could only be indirectly inferred on the basis of conventional electrical and optical characterization.