3D-mapping and manipulation of photocurrent in an optoelectronic diamond device

Abstract: Characterising charge transport in a material is central to the understanding of its electrical properties, and can usually only be inferred from bulk measurements of derived quantities such as current flow. Establishing connections between host material impurities and transport properties in emerging electronics materials, such as wide bandgap semiconductors, demands new diagnostic methods tailored to these unique systems, and the presence of optically-active defect centers in these materials offers a non-perturbative, in-situ characterisation system. Here, we combine charge-state sensitive optical microscopy and photoelectric detection of nitrogen-vacancy (NV) centres to directly image the flow of charge carriers inside a diamond optoelectronic device, in 3D and with temporal resolution. We optically control the charge state of background impurities inside the diamond on-demand, resulting in drastically different current flow such as filamentary channels nucleating from specific, defective regions of the device. We then optically engineered conducting channels that control carrier flow, key steps towards optically reconfigurable, wide bandgap designer optoelectronics. We anticipate our approach might be extended to probe other wide-bandgap semiconductors (SiC, GaN) relevant to present and emerging electronic technologies.