Changes of structure and optical energy gap induced by oxygen pressure during the deposition of ZnO films

Highly c-axis oriented ZnO thin films were deposited by laser ablating Zn target in oxygen atmosphere at room temperature. Changes of c-axis lattice constant and optical energy gap caused by oxygen defects were studied via the control of oxygen vacancy concentration afforded by changing oxygen pressure in the deposition process. The results show that ZnO thin films prepared at room temperature have a very strong preferred c-axis growth orientation. As oxygen pressure increases, the lattice constant c decreases, and optical energy gap shifts towards higher energy values.