Microwave plasma deposited (100) diamond films have been thermally oxidized in dry O2 between 500 and 723 degrees C. The roughness of a single crystalline grain following oxidation is consistent with a layer-by-layer mechanism for the removal of carbon monoxide. The resulting surface exhibits infrared absorption bands at 1731 and 905 cm-1, attributed to the stretching and bending modes of a surface bonded carbonyl group. The former is within 1 cm-1 of the structurally analogous molecule 2-adamantanone. These data are consistent with the carbonyl groups being present on diamond (100) terraces.
The surface morphology, electronic structure and atomic bonding configurations of chemical vapor deposition ͑CVD͒ diamond films prepared at different stages of the deposition process and subjected to different postdeposition surface treatments have been studied by scanning probe microscopy ͑SPM͒, scanning tunneling spectroscopy ͑STS͒, and x-ray photoelectron spectroscopy ͑XPS͒ surface analysis techniques. SPM image observations show that ͑a͒ in the biasing nucleation process, diamond crystallites grow in a three-dimensional manner and the nucleation density reaches 10 9 -10 10 /cm 2 ; ͑b͒ both as-deposited and boron ion implanted films exhibit a hillock morphology on ͑100͒ crystal faces; ͑c͒ atomic flatness can be achieved on crystal faces by hydrogen plasma etching. STS analysis indicates that ͑i͒ the films obtained after an initial biasing nucleation process show a metallic tunneling behavior; ͑ii͒ both as-deposited and hydrogen plasma etched CVD diamond films possess typical p-type semiconductor surface electronic properties; ͑iii͒ when the as-deposited diamond films are subjected to boron implantation or argon ion etching, the surface electronic properties change from p-type semiconducting behavior to metallic behavior. XPS analysis confirmed that the surfaces for both as-deposited and hydrogen plasma etched diamond films have a tetrahedral atomic bonding configuration. However, the surfaces of boron ion implanted and argon ion etched diamond films exhibited an amorphous carbon-like feature which can be attributed to the surface damage caused by ion bombardment.
The surface morphology and electronic properties of as-deposited CVD diamond ®lms and the diamond ®lms which have been subjected to boron ion implantation or hydrogen plasma etching have been systematically studied by high resolution scanning probe microscopy and spectroscopy techniques. AFM and STM image observations have shown that (a) both the as-deposited CVD diamond ®lms and the boron ion implanted ®lms exhibit similar hillock morphologies on (100) crystal faces and these surface features are formed during the deposition process; (b) boron ion implantation does not cause a discernible increase in surface roughness; (c) atomic¯atness can be achieved on crystal faces by hydrogen plasma etching of the ®lm surface. Scanning tunnelling spectroscopy analysis has indicated that (a) the as-deposited diamond ®lms and the hydrogen plasma etched diamond ®lms possess typical p-type semiconductor surface electronic properties; (b) the as-deposited diamond ®lms subjected to boron implantation exhibit surface electronic properties which change from p-type semiconducting behaviour to metallic behaviour; (c) the damage in the boron implanted diamond ®lms is restricted to the surface layers since the electronic properties revert to p-type on depth pro®ling.Key words: CVD diamond ®lms; surface morphology and electronic structure; scanning probe microscopy and spectroscopy.
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