Tailoring pulsed laser deposition fabricated copper oxide film by controlling plasma parameters

Various copper oxide stoichiometries have been grown by Pulsed Laser Deposition (PLD) on MgO (100). The role of oxygen pressure on the structural and physical properties of the films was investigated in the 1·10 –5 Pa – 1 Pa range. Positron annihilation spectroscopy revealed positrons trapped at vacancies and large vacancy clusters with lifetimes ranging from 400 ps to 500 ps. Different stoichiometries were found to be dominated by characteristic vacancies. Single copper vacancies V Cu are found for CuO phase with good indication for p-type applications while for the Cu 2 O complexes of copper vacancies coupled with oxygen vacancies (V Cu + V O and V Cu + 2V O ) are seen. Particular O 2 atmosphere conditions induce a mixture of copper oxide phases with the CuO crystals growing on top of Cu 2 O films. The deposition process was monitored with in situ diagnostic techniques based on optical emission spectroscopy and Langmuir probe method. The kinetics of the plasma during the deposition process are well correlated with the properties of the deposited films.
The monitoring tools define clear energetic threshold for the formation of CuO or Cu 2 O phases.