Physical property characterization of Cu _x(1,2) o nanofilms grown on (100) silicon by thermal copper oxidation

Cuprous oxide (Cu ₂ O) and cupric oxide (CuO) films of nanometric thicknesses on monocrystalline (100) silicon were grown by thermal cupper oxidation technique. The copper nanofilms were deposited on crystalline (100) silicon by autocatalysis using watery solutions based on copper sulphate (CuSO ₄ ) and hydrofluoric acid (HF). The Cu ₂ O was obtained at an annealing temperature of 200ºC, whereas for the CuO was necessary to use a higher oxidation temperature, 600ºC for 3 h. The thicknesses of the copper oxide layers were ranged from 30 to 150 nm obtained by ellipsometry. For the characterization of the oxidized copper layers, cuprous and cupric of oxides, were used different techniques. In order to examine the surface morphology of the films atomic force microscopy (AFM) was used and for the identification of the different oxides crystalline phases was used X-ray diffraction. By means of the Debye-Scherrer equation the nanocrystal size that forms the copper-based nanofilms was estimated. For the Cu nanofilm in the diffraction peak (111), a crystal size of 16.82 nm is obtained. Similarly, for Cu ₂ O, the nanocrystal size is 8.11 nm and for the CuO, the size is 6.66 nm, which indicates that crystal size depends of the annealing temperature. The refractive indexes measured for the nanofilms oxidized at 200ºC was from 2.2-2.3 and for the obtained ones at 600ºC was from 2.7-2.9.