9322412 Drabold This is a new award for computationally-intensive theoretical research to study tetrahedral amorphous carbon. It has recently been demonstrated that a fourfold-coordinated form of amorphous carbon, tetrahedral amorphous carbon, is a semiconductor; can be doped both positive and negative; shows photoconductivity and has been employed to make simple devices. A theoretical research program will be undertaken to determine the properties of this material. The research will provide detailed studies of the atomic scale structure and electrical properties using first principles methods. Defects in the amorphous network will be identified and their effects on carrier transport will be examined. The properties of several impurities, but especially the demonstrated shallow donors, will be explored. A limited study of the effects of hydrogen on material properties will be performed. The surface structure of the material will be determined with a view to producing surface structural models that will be useful to future atomistic or Monte Carlo growth studies. The vibrational properties and stability of the material will also be investigated. A complementary effort will be directed toward improvement of the efficiency of existing computational techniques for first principles simulations of tetrahedral amorphous carbon and other chemically bonded materials. %%% This is a compuational research project to study the properties of an amorphous form of carbon. This material has been shown to have many interesting properties which may have significant impact on microelectronics - not the least of which is that it is a semiconductor. Thus, the material seems to have many of the desirable electronic properties of diamond. The research will provide one of the first comprehensive theoretical studies of this new material. ***
