XPS and UPS investigation of the diamond surface oxidation by UV irradiation

In this work we describe the effect of oxidation on undoped nanocrystalline H-terminated CVD diamond films. Surface oxidation was performed using UV photons in air and in pure dry oxygen atmosphere. The samples were then thermally treated to study the effect of the UV-induced oxidation on the electronic properties of diamond. Different annealing temperatures were applied to induce a controlled oxygen desorption. Both UV- and X-ray photoelectron spectroscopies were performed in situ in order to correlate the electron affinity changes to the oxygen atomic abundances detected on the diamond surfaces. Our results show that UV oxidation is less invasive if compared to other conventional processes like chemical or plasma oxidations. This enables a recovering of the surface electronic properties with the thermal desorption of oxygen from the diamond surfaces.