| The purpose of this research is to understand the electrical conduction mechanisms of heteroepitaxial diamond by performing direct current (DC) electrical measurements. Of particular interest is the temperature dependence of the DC conductivity. The project takes advantage of recent advances at Michigan State University in the growth of diamond by chemical vapor deposition on lattice-matched substrates, i.e., by heteroepitaxy. This investigation represents the first detailed study of an electrical transport property of heteroepitaxial diamond. The characterization of the electrical properties of a wide bandgap, high resistivity material such as diamond requires low current, high temperature measurements. A number of new techniques were developed to perform reliable electronic measurements at elevated temperatures. The magnitude of the DC conductivity of heteroepitaxial diamond was found to be remarkably similar to that of high-purity, Type IIa natural diamond. Heteroepitaxial diamond exhibits thermally activated conductivity, with a single activation energy of 1.40+/-0.03 eV from 250 °C to 550 °C. This result is similar to previous measurements by other workers on Type Ila natural diamond, suggesting the presence of electronic states at comparable concentrations in materials of completely different origin. |
