Study of Oxygen on the Three Low Index Diamond Surfaces by XPS

Abstract

Nominally clean diamond surfaces have been shown to contain adsorbed foreign atoms on them. Some of the adsorbed atoms have also been known to lead to various surface modifications, a phenomenon that is important in diamond electronics. Establishing the identity and nature of the adsorbed atoms on these surfaces is therefore key to the successful application of diamond in various technological fields. In this work, X-ray photoelectron spectrometry (XPS) has been used to investigate the three low index diamond surfaces. The results show oxygen as the main foreign atom on these surfaces other than hydrogen, with varying fractions of oxygen monolayer coverage being observed. It is further established that the adsorbed oxygen exists in several bonding configurations, with the energy shifts associated with the various functional groups being determined.

Nanostructuring and oxidation of diamond by two-photon ultraviolet surface excitation: An XPS and NEXAFS study

“…2). Comparison of the separations of subpeak binding energies from the main sp 3 peak with results obtained in other reports [14,18,24,[28][29][30] allowed the attribution of the higher binding energy subpeaks to single and double oxygen bonded carbon. The double bonded oxygen subpeak is assumed to be primarily due to ketone (C=O) groups, while the single bonded carbon subpeak may be due to either ether (C−O−C), hydroxyl (C−OH), or a mixture of both.…”

“…The uncertainty in peak locations and areas correspond to estimates based on manual iteration of parameters that produce a negligible residual trace. to ketone groups [14]. For the unetched (100) surface, the FWHM of the ketone peak is greater than that observed in other spectra, and its separation from the singly bonded oxygen peak is anomalously small.…”

“…However, there are few reported results for O(1s) XPS binding energies for diamond surfaces in the literature and amongst these results there is some disagreement in the identification of subpeaks. The authors are aware of only two O(1s) XPS studies of single crystal diamond: Makau and Derry [14] reported binding energies of 531.5 eV, 532.2 eV, and 533.1 eV for ketone, hydroxyl, and ether groups, respectively, while Petrick et al reported 532.5 eV for ketone and 532.3 eV for hydroxyl, and no ether energy was identified. Due to the apparent close spacing of hydroxyl and ether peaks and the uncertainty in their locations, we were unable to deconvolve these two groups.…”

“…The chemical environment of a diamond surface is complex and has been found to depend strongly on the crystal facet orientation and the method of surface preparation. The total amount of oxygen on a fully oxidized diamond surface varies with the type of crystallographic face-(100) surfaces saturate at 0.5 ML, while (110) and (111) faces saturate at 0.33 ML [13][14][15]. The (100) surface supports a mixture of C−O−C (ether), C−OH (hydroxyl), and C=O (ketone) groups at lower coverages, that becomes dominated by ethers as the coverage increases [16][17][18].…”

Diamond-Like Carbon Nanofoam from Low-Temperature Hydrothermal Carbonization of a Sucrose/Naphthalene Precursor Solution

“…For diamond crystal surfaces, adsorbed oxygen exists in several functional surface groups [101]. The carbon-oxygen interaction of the diamond surface has been investigated and the oxidized diamond surface has been found to be hydrophilic [102].…”