Abstract
Introducing a cluster formation model, we provide a rational fundamental viewpoint for the difficulty to achieve n-type doped diamond. We argue that codoping is the way forward to form appropriately doped shallow regions in diamond and other forms of carbon such as graphene. The electronegativities of the codopants are an important design criterion for the donor atom to efficiently donate its electron. We propose that the nearest neighbour codopants should be of a considerably higher electronegativity compared to the donor atom. Codoping strategies should focus on phosphorous for which there are a number of appropriate codopants. (C) 2011 American Institute of Physics. [doi:10.1063/1.3633223]