ELECTRICAL CHARACTERIZATION OF CVD DIAMOND THIN-FILMS GROWN ON SILICON SUBSTRATES

Diamond thin films grown on high resistivity, (100) oriented silicon s ubstrates by the hot filament chemical vapor deposition (HFCVD) method have been characterized by four-point probe and current-voltage (thro ugh film) techniques. The resistivities of the as-grown, chemically et ched and annealed samples lie in the range of 10(2) Ohm cm to 10(8) Oh m cm. The Raman measurements on these samples indicate sp(3) bonding w ith a sharp peak at 1332 cm(-1). The surface morphology as determined by scanning electron microscope shows polycrystalline films with (100) or (111) faceted structures with average grain size of approximate to 2.5 mu m. The through film current-voltage characteristics obtained v ia indium contacts on these diamond films showed either rectifying or ohmic behavior. The difference in Schottky and ohmic behavior is expla ined on the basis of the high or low sheet resistivities measured by f our-point probe technique. 5% methane to hydrogen concentration during film growth resulted in poor surface morphology, absence of sp(3) bon ds, and low resistivity.