Effects of oxygen on diamond growth using platinum substrates

Publisher Website
Google Scholar
Abstract
The effect of gas phase oxygen on chemical vapor deposition diamond growth on Pt substrates was studied using x-ray photoelectron spectroscopy (XPS). Samples were transferred between the diamond growth chamber and an attached ultrahigh vacuum analysis chamber without exposure to air. The time-dependent evolution of surface carbon species was monitored by interrupting growth at specific times and analyzing the surface with XPS. In this paper we compare samples prepared from four different mixtures of H2/CH4/O2. With low gas phase O/C ratios (≤0.5) diamond growth on Pt proceeds by a three-step mechanism: (1) decomposition of surface contaminants to form graphitic carbon, (2) conversion of these graphitic species to stable hydrocarbon species, (3) replacement of hydrocarbons with diamond. At higher gas phase O/C ratios (≥0.75) we observed that the Pt surface had less than 1 ML of carbon. In other words, the surface was very clean, and diamond growth did not occur at a measurable rate. However, once diamond is nucleated on the surface under conditions of low oxygen concentration, diamond growth proceeds readily using a high oxygen feed with O/C=1. We conclude that the addition of oxygen affects diamond formation primarily by decreasing the nucleation rate on metals like Pt. Growth rates of existing diamond films are not strongly affected by oxygen.

This publication has 14 references indexed in Scilit: