Excimer laser sputtering deposition of TiO2 optical coating for solar cells

We have investigated the ArF laser sputtering deposition of TiO2 anti-reflection coatings, aiming at large scale production of II-VI and III-V solar cells, the main theme of our research group. As a first step, layers were deposited on silicon wafers and glass. A reasonable growth rate for production, considering possible pulse frequencies of a few tens Hertz, of 0.1 Angstrom per 1 J/cm(-2) laser pulse energy density was obtained. The structure of the oxide layer, interface and interdiffusion with the substrate are characterized using cross sectional high resolution transmission electron microscopy and Rutherford backscattering, as a function of substrate temperature on the one hand and argon, nitrogen and oxygen pressure during deposition on the other hand. The surface optical quality of the deposited films versus thickness and growth conditions is presented. We will apply this technique to a solar cell prototype and a GaSb based photodetector prototype fabricated in our group.