Characterization of the surface morphology and electronic properties of microwave enhanced chemical vapor deposited diamond films

Abstract

The surface morphology, electronic structure and atomic bonding configurations of chemical vapor deposition (CVD) diamond films prepared at different stages of the deposition process and subjected to different postdeposition surface treatments have been studied by scanning probe microscopy (SPM), scanning tunneling spectroscopy (STS), and x-ray photoelectron spectroscopy (XPS) surface analysis techniques. SPM image observations show that (a) in the biasing nucleation process, diamond crystallites grow in a three-dimensional manner and the nucleation density reaches 109–1010/cm2; (b) both as-deposited and boron ion implanted films exhibit a hillock morphology on (100) crystal faces; (c) atomic flatness can be achieved on crystal faces by hydrogen plasma etching. STS analysis indicates that (i) the films obtained after an initial biasing nucleation process show a metallic tunneling behavior; (ii) both as-deposited and hydrogen plasma etched CVD diamond films possess typical p-type semiconductor surface electronic properties; (iii) 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.