Studies on tuning surface electronic properties of hydrogenated diamond by oxygen functionalization

TL;DR

This study demonstrates how oxygen functionalization can effectively tune the electronic properties of hydrogenated diamond films, transforming their surface chemistry and electrical conductivity, with potential implications for diamond-based electronic devices.

Contribution

It provides new insights into surface charge transfer doping mechanisms and the effects of oxygen functionalization on the electronic structure of hydrogenated diamond films.

Findings

Surface resistance increases from ~8 kohms/sq to over 10 Gohms/sq with ozonation.

Higher current conduction occurs on grain interiors and (111) planes compared to grain boundaries and (100) planes.

Fully oxygen-terminated diamond surfaces show no current flow, indicating surface passivation.

Abstract

Ultra-wide bandgap and the absence of shallow dopants are the major challenges in realizing diamond based electronics. However, the surface functionalization offers an excellent alternative to tune electronic structure of diamonds. Herein, we report on tuning the surface electronic properties of hydrogenated polycrystalline diamond films through oxygen functionalization. The hydrogenated diamond (HD) surface transforms from hydrophobic to hydrophilic nature and the sheet resistance increases from ~ 8 kohms/sq. to over 10 Gohms/sq. with progressive ozonation. The conductive atomic force microscopic (c-AFM) studies reveal preferential higher current conduction on selective grain interiors (GIs) than that of grain boundaries confirming the surface charge transfer doping on these HDs. In addition, the local current conduction is also found to be much higher on (111) planes as compared to (100) planes on pristine and marginally O-terminated HD. However, there is no current flow on the fully O-terminated diamond (OD) surface. Further, X-ray photoelectron spectroscopic (XPS) studies reveal a redshift in binding energy (BE) of C1s on pristine and marginally O-terminated HD surfaces indicating surface band bending whilst the BE shifts to higher energy for OD. Moreover, XPS analysis also corroborate c-AFM study for the possible charge transfer doping mechanism on the diamond films which results in high current conduction on GIs of pristine and partially O-terminated HDs.