Increased thermal stability of Al-doped ZnO-based transparent conducting electrodes employing ultra-thin Au and Cu layers

Abstract The paper examines the influence of heating in air on the structural, electrical and optical properties of Al-doped ZnO (AZO)-based transparent conducting electrodes employing ultra-thin Au and Cu layers, sputter-deposited onto unheated glass substrates. The results are compared with the ones obtained for single AZO layers. For these, the quality factor in the visible wavelength range degrades continuously with the heating temperature, as the result of increasing sheet resistance. Contrary to this behavior, symmetric AZO/Au/AZO and AZO/Cu/AZO trilayers improve their quality factor for temperatures up to 250 °C. At the same time, these trilayers offer 4-times lower roughness than single AZO layers of comparable sheet resistance, which can be a significant advantage when active optoelectronic or solar-cell device layers are to be deposited on the transparent electrode.