A Theoretical Study of the Energetic Stability and Electronic Structure of Terminated and P-Doped Diamond (100)-2x1 Surfaces

Abstract

Shuainan Zhao and Karin Larsson

The combined effect of P-doping and surface-termination on the energetics, and especially the electronic structure, of a diamond (100) surface, has in the present study been investigated by using a Density Functional Theory method. The diamond surface was terminated with any of the following species: H, F, OH, Obridge and NH2 . These adsorbates have earlier experimentally been proven crucial for e.g. applications based on surface electrochemistry. The observed results were analysed with the purpose to obtain a deeper knowledge about the atomic-level cause to the observed effects by the P doping and surface termination. The P dopant was found to have a very minor influence on the averaged adsorption energy for the various terminating species (i.e. with less than 0.17 eV). Moreover, the adsorbates were found to reduce the stability of the P-dopant in the diamond lattice. When analysing the results of the calculated partial density of states, the P dopant was found to contribute with band gap states below the conduction band, out of which one is a donor band. In addition, the surfaces with their terminating species will contribute with empty band gap states just below the CBM of the diamond surfaces. Hence, the combination of P doping and surface termination will induce both donor and acceptor states in the diamond surface band gap, which will improve the usefulness of these specific diamond surfaces in various electronic devices. The work function of a diamond surface is one specific properties that will be affected by substitutional doping and surface termination. Within the present study, the terminating species were found to render a strong impact on the surface work function (as compared to a non-terminated diamond (100)-2x1 surface), with calculated work function values that were even further decreased by P-doping.

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