Effect of oxygen gas pressure on electrical, optical, and structural properties of Al-doped ZnO thin films fabricated by pulsed laser deposition for use as transparent electrodes in all-solid-state electrochromic devices

Low-resistivity and high-transmittance Al-doped ZnO (AZO) thin films were obtained by pulsed laser deposition with the substrate at room temperature. The electrical, optical, and structural properties of the AZO thin films deposited at various oxygen gas pressures (P_O2) were investigated. X-ray diffraction shows that the AZO thin films have (002) preferred orientation and the diffraction angle of the (002) plane shifts to a higher value with increasing oxygen gas pressure. All AZO thin films deposited under ambient oxygen gas pressure conditions have an optical transmittance of over 80% in the visible region. AZO thin films deposited at lower P_O2 of ≤1 Pa have resistivities of <10^-3 Σ cm that increase with increasing P_O2 > 1 Pa. The AZO film deposited at P_O2 = 1 Pa had the lowest resistivity (5:8 × 10^-4 Ω cm) with a high carrier concentration of 1.1 × 10²¹ cm^-3.