Micro- to nano-scale topographical etching of diamond substrate via anisotropically atomic removal

Abstract

Substrate functionalization of diamond semiconductors rely on micro- and nano-topographical shapes and dimensions. However, an efficient and controllable fabrication is challenging due to its high hardness. In this study, a micro- to nano-scale etched topography model is proposed on the machined diamond substrate related to graphitization along crystal orientation. The objective is to explore how to control the structured dimensions based on atomic scale removal. First, the formation model of the etched structure was established in relation to thermal oxidation and graphitization, etc. Then, experiments were conducted to compare the structure size of the natural crystal surface. Finally, the etched structure dimension on the substrate was theoretically analyzed and experimentally characterized. It is shown that the dimension of etched structures depends on the rate of C atoms escaping layer by layer as CO/CO2 molecules with graphitization. The oxidative etching rate shows an increasing change in temperature. The degree of graphitization is enhanced as it approaches the (111) surface. At the macro scale, the structured size is subject to crystal orientation, environmental temperature, and catalysis. As a result, the micro- and nano-scale structures of the diamond substrate may be transferred to each other by the etching along crystal orientation.