Identification of defects and the origins of surface noise on hydrogen-terminated (100) diamond

TL;DR

This study combines microscopy and simulations to identify surface defects on hydrogen-terminated diamond, revealing their structures and origins of noise, and demonstrating defect control methods relevant for quantum device fabrication.

Contribution

It provides the first atomic-level identification of surface defects on CVD-grown diamond and links these defects to magnetic noise and charge trapping in quantum applications.

Findings

Identified atomic structures of surface defects on H:C(100)-2x1 diamond surfaces.

Linked specific defects to magnetic noise and charge trapping.

Demonstrated defect manipulation via STM tip control.

Abstract

Near-surface nitrogen-vacancy centres are critical to many diamond-based quantum technologies such as information processors and nanosensors. Surface defects play an important role in the design and performance of these devices. The targeted creation of defects is central to proposed bottom-up approaches to nanofabrication of quantum diamond processors, and uncontrolled surface defects may generate noise and charge trapping which degrade shallow NV device performance. Surface preparation protocols may be able to control the production of desired defects and eliminate unwanted defects, but only if their atomic structure can first be conclusively identified. This work uses a combination of scanning tunnelling microscopy (STM) imaging and first-principles simulations to identify several surface defects on H:C(100)-2x1 surfaces prepared using chemical vapour deposition (CVD). The atomic structure of these defects is elucidated, from which the microscopic origins of magnetic noise and charge trapping is determined based on modelling of their paramagnetic properties and acceptor states. Rudimentary control of these deleterious properties is demonstrated through STM tip-induced manipulation of the defect structure. Furthermore, the results validate accepted models for CVD diamond growth by identifying key adsorbates responsible for nucleation of new layers.