Ab initio study of the passivation and interaction of substitutional impurities with hydrogen in diamond

The production of n-type doped diamond has proved very difficult. Since boron, a shallow acceptor, can be passivated by hydrogen, it is possible that some of the difficulties in producing electrically active donors could be due to passivation by hydrogen which is present during the CVD growth of diamond. We report ab initio modelling of the interaction of hydrogen with boron, phosphorus and sulfur in diamond, and show that it is energetically favourable for hydrogen to bind to these centres and passivate them. We further investigated the possibility of the trapping of a second hydrogen atom at these centres, where we found that the complexes consisting of a dopant and two hydrogen atoms are energetically favourable for sulfur, with a binding energy similar to that found for H-2* in diamond. (C) 2002 Elsevier Science B.V. All rights reserved.