ELECTRICAL-PROPERTIES OF DIAMOND THIN-FILMS GROWN BY CHEMICAL-VAPOR-DEPOSITION TECHNIQUE

Diamond thin films grown on high resistivity, [100]-oriented silicon s ubstrates by the hot filament chemical vapor deposition method have be en characterized by four-point probe and Hall effect measurements. The resistivities of both as-grown and chemically etched samples were low er than expected. The Raman spectra showed dramatic changes from two b road bands (one starting at 1250 cm(-1) and peaking at 1350 cm(-1) and the other starting at 1500 cm(-1) and peaking at 1580 cm(-1)) for the as-grown samples to a sharp peak centered at 1332 cm(-1) with a full width at half-maximum of 10.7 cm(-1) for the chemically treated sample . Hall measurements yielded carrier concentrations in the temperature range 180-300 K. From a plot of carrier concentration vs. inverse temp erature, activation energies of 0.36 and 0.20 eV are obtained for the two chemically treated samples. The resistivity values at room tempera ture of 100 Ohm cm are significantly lower than the values recently ob served for other undoped samples (p = 10(3)-10(4) Ohm cm). The low res istivity values observed in this work are attributed to the disordered graphitic regions between the diamond crystalline grains.