Electronic structure of doped fourfold coordinated amorphous semiconductors. Midgap states in amorphous carbon

Midgap states have been studied in phosphorus-doped, tetrahedrally coordina ted amorphous carbon by means of the Fragment Self-Consistent Field method (FSCF). It has been found that the midgap energy levels are primarily deter mined by the relative position of dopants. A simple linear correlation has been obtained between the highest occupied molecular orbital (HOMO) energy of the model clusters and the inverse distance of impurities. (C) 1999 Else vier Science B.V. All rights reserved.