Highly Transparent and Low Resistivity Al-doped ZnO Thin Films Grown by Pulsed Laser Deposition under Different Oxygen Flow Rates

Polycrystalline Al-doped ZnO (AZO) thin films with a thickness of 1300 A were grown on Corning 1737 glass by pulsed laser deposition (PLD) at a low substrate temperature. The presence of oxygen gas during deposition led to a remarkable enhancement of the (002) c-axis preferential orientation as well as increased crystallite size. Highly transparent films with a transmittance of 85% could be obtained by controlling the oxygen flow rate, while causing a Burstein-Moss shift toward a shorter wavelength as well. The resistivities of the films were found to be functions of both the oxygen flow rate and substrate temperature, with the lowest value being 2.3 x 10(-4) Omega.cm (18 Omega/sq sheet resistance). It was found that both the oxygen flow rate and substrate temperature are crucial in order to grow superior device quality films with an appropriate degree of crystallinity, less surface roughness, high transmittance and low resistivity, which are characteristics of great technological importance.