COMMUNICATION (1 of 8)Diamond materials are central to an increasing range of advanced technological demonstrations, from high power electronics to nanoscale quantum bioimaging with unprecedented sensitivity. [1] However, the full exploitation of diamond for these applications is often limited by the uncontrolled nature of the diamond material surface, which suffers from Fermi-level pinning and hosts a significant density of electromagnetic noise sources. [2] These issues occur despite the oxide-free and air-stable nature of the diamond crystal surface, which should be an ideal candidate for functionalization and chemical engineering. In this work, a family of previously unidentified and near-ubiquitous primal surface defects, which are assigned to differently reconstructed surface vacancies, is revealed. The density of these defects is quantified with X-ray absorption spectroscopy, their energy structures are elucidated by ab initio calculations, and their effect on near-surface quantum Many advanced applications of diamond materials are now being limited by unknown surface defects, including in the fields of high power/ frequency electronics and quantum computing and quantum sensing. Of acute interest to diamond researchers worldwide is the loss of quantum coherence in near-surface nitrogen-vacancy (NV) centers and the generation of associated magnetic noise at the diamond surface. Here for the first time is presented the observation of a family of primal diamond surface defects, which is suggested as the leading cause of band-bending and Fermi-pinning phenomena in diamond devices. A combination of density functional theory and synchrotron-based X-ray absorption spectroscopy is used to show that these defects introduce low-lying electronic trap states. The effect of these states is modeled on band-bending into the diamond bulk and it is shown that the properties of the important NV defect centers are affected by these defects. Due to the paramount importance of near-surface NV center properties in a growing number of fields, the density of these defects is further quantified at the surface of a variety of differently-treated device surfaces, consistent with best-practice processing techniques in the literature. The identification and characterization of these defects has wide-ranging implications for diamond devices across many fields.
We report the preparation of an ordered silicon terminated diamond (100) surface with a two domain 3 Â 1 reconstruction as determined by low energy electron diffraction. Based on the dimensions of the surface unit cell and on chemical information provided by core level photoemission spectra, a model for the structure is proposed. The termination should provide a homogeneous, nuclear, and electron spin-free surface for the development of future near-surface diamond quantum device architectures. V
In situ X-ray spectroscopies offer a powerful way to understand the electronic structure of the electrode-electrolyte interface under operating conditions. However, most X-ray techniques require vacuum, making it necessary to design spectro-electrochemical cells with a delicate interface to the wet electrochemical environment. The design of the cell often dictates what measurements can be done and which electrochemical processes can be studied. Hence, it is important to pick the right spectro-electrochemical cell for the process of interest. To facilitate this choice, and to highlight the challenges in cell design, we critically review four recent, successful cell designs. Using several case studies, we investigate the opportunities and limitations that arise in practical experiments.
A combination of synchrotron-based x-ray spectroscopy and contact potential difference measurements have been used to examine the electronic structure of the (3 × 1) silicon terminated (100) diamond surface under ultra high vacuum conditions. An occupied surface state which sits 1.75 eV below the valence band maximum has been identified, and indications of mid-gap unoccupied surface states have been found. Additionally, the pristine silicon terminated surface is shown to possess a negative electron affinity of -0.86 ± 0.1 eV.
An ordered germanium terminated (1 0 0) diamond surface has been formed and characterised using a combination of low energy electron diffraction and synchrotron-based core level photoemission spectroscopy. A number of preparation methods are explored, in each case inducing a two domain [Formula: see text] surface reconstruction. The surface becomes saturated with bonded germanium such that each [Formula: see text] unit cell hosts 1.26 Ge atoms on average, and possesses a negative electron affinity of -0.71 eV.
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