ILLUMINATION-INDUCED SURFACE-CHARGES ON THIN DIAMOND FILMS AT DIFFERENT WAVELENGTHS

Contact angle studies of pure water droplets were carried out on thin diamond films. The films were deposited on a fresh Si [111] wafer by p lasma assisted chemical vapour deposition (PACVD) and confirmed to be diamond by Raman spectroscopy and scanning electron microscopy. Advanc ing and receding contact angles were measured as a function of droplet volume by using different incident wavelengths: red, green and violet . Large differences in the contact angles were observed, depending on the wavelength of the incident light. These differences are usually re lated to the existence of illumination-induced surface charges or elec tromagnetically active inhomogeneities in the diamond films. The resul ts show that this technique is sufficiently sensitive to correlate cha nges in the contact angle with changes in the wavelength used.