  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.
