ELECTRONIC CHARACTERIZATION OF DIAMOND FILMS PREPARED BY ELECTRON-CYCLOTRON-RESONANCE MICROWAVE PLASMA

Diamond films with different surface morphologies were produced by the electron cyclotron resonance microwave-plasma-assisted CVD method from gas mixtures containing CO-H-2-O2 at a relatively low pressure. The electrical conductivity of the samples along the growth direction was measured in the temperature range from 200 to 800-degrees-C. The films with (111) morphologies have conductivity activation energies of between 0.3 and 0.4 eV consistent with boron incorporation in such films. On the contrary, films with (100) morphologies have a conductivity activation energy of 1.5 eV consistent with nitrogen incorporation in such films. Electron spin resonance and cathodoluminescence measurements show the simultaneous existence of boron and nitrogen impurities. Owing to their high solubility, boron and nitrogen are the most common impurities in natural and synthetic diamonds. The results suggest that electrically active boron and nitrogen incorporation takes place more efficiently when growth proceeds along the (111) and (100) directions respectively.