Temperature programmed desorption of hydrogen and deuterium from CVD diamond samples

The desorption kinetics of H2, HD, and D2 from a CVD- grown diamond sample have been measured using temperature programmed desorption. The sample was exposed to hydrogen and deuterium at ∼100K. Molecular hydrogen does not react with the diamond surface but atomic hydrogen chemisorbs. The sample is then heated to 1500 K at a rate of 6 K/s. The hydrogen desorption spectrum from these polycrystalline specimens is surprisingly simple, consisting of a single peak near 1270 K for all coverages studied. The width of the desorption peak is ∼100K. Neither the width nor the peak maximum shift with increasing hydrogen coverage. The is no isotope effect to the desorption. No other desorption products (water, small hydrocarbons) are detected. Kinetic parameters can be extracted from these spectra, and these can be compared to hydrogen desorption from natural diamond single crystal surfaces. These parameters can be used to model diamond growth processes