Atomic layer deposition of B2O3 thin films at room temperature

Atomic layer deposition of boron oxide thin films was demonstrated at room temperature using BBr3 and H2O as precursors. Crystallinity of the films was characterised by X-ray diffraction while time-of-flight elastic recoil detection analysis (TOF-ERDA) and X-ray fluorescence were used to analyse stoichiometry and possible impurities. As-deposited films were amorphous and reacted readily with the atmosphere if not protected by an alumina overlayer. Boron oxide deposition rate of 0.76 Å per cycle was obtained at 20 °C. If the deposition temperature was increased to 50 °C and above, almost no film growth could be obtained. According to the TOF-ERDA, hydrogen and carbon contents in the films were very low being less than 0.2 and 0.1 at.%, respectively.