Surface Cleaning, Topography, and Temperature Measurements of Single Crystal Diamond

ABSTRACTApplication of surface science methods to single crystal diamond surfaces requires the preparation of clean, well-ordered surfaces and accurate measurement of substrate temperature. Cleaning of diamond (100) in H2SO4/HNO3/HClO4 produced several infrared absorption features between 1025 and 1275 cm-1, as observed by infrared multiple-internal-reflection spectroscopy. These modes are assigned to surface hydroxyl and bridge-bonded oxygen. Heating an oxidized surface to ca. 1130 °C caused disappearance of a surface hydroxyl mode centered at 1080 cm-1. We show by atomic force microscopy that an as-polished diamond (100) sample is covered by grooves and ridges several nm in height, implying a modest density of atomic steps. The surface of a diamond that underwent etching via numerous adsorption/desorption experiments in ultrahigh vacuum and was acid cleaned several times was essentially unchanged, indicating a minimal perturbation of the surface topography. The capability of Fizeau interferometry for accurate measurement of single-crystal diamond temperatures is demonstrated.