A New Probe for In-Situ Characterization of Diamond Surfaces During Low Pressure Chemical Vapor Deposition

Abstract

Single crystal diamond has extremely high thermal conductivity, a large bandgap, high carrier mobilities, and low neutron and ionizing radiation dislocation cross sections. These physical properties make it an ideal material in which to fabricate electronic devices for high temperature, high frequency and/or high radiation service. Despite the significant body of work to date on low pressure chemical vapor deposition (LPCVD) of diamond, no methods now exist for manufacturing the large single crystal diamond substrates required to realize these potentials. It has become clear that the fundamental mechanisms of diamond’s nucleation and growth must be determined before we can significantly improve its process technology. Prior research, focussing on the gas phase chemistry in diamond LPCVD systems, has provided some valuable clues to possible mechanisms. However, chemical transport through the boundary layer to the substrate is still rather mysterious, and any conclusions about the environment at the growing surface based upon gas phase data are speculative at best. Our contribution to the field is the first direct probe for diamond surface chemistry under LPCVD growth conditions: in-situ direct recoil spectroscopy (DRS). In conjunction with the earlier gas phase results, this new tool will give us the first comprehensive description of diamond LPCVD, enabling relatively straightforward determinations of both chemical mechanisms and improved process conditions for diamond growth.