Electrical and optical properties of radio frequency magnetron-sputtered lightly aluminum-doped zinc oxide thin films deposited in hydrogen–argon gas

• Electrical and optical properties of lightly Al-doped ZnO (L-AZO) thin films.
• Films studied under various deposition conditions.
• Carrier concentration (CC) and transmittance for thickness > 100 nm is studied.
• For thin L-AZO films, CC and transmittance depend on O vacancies and interstitial H atoms.

We studied the electrical and optical properties of lightly aluminum-doped zinc oxide (L-AZO) films, which were deposited on soda-lime glass substrates by radio frequency (RF) magnetron sputtering using a 0.2 wt.% aluminum-doped zinc oxide target and a 0.3 wt.% hydrogen-mixed argon (Ar/0.3% H2) gas. The L-AZO films were characterized in terms of structural, optical, and electrical properties by X-ray diffraction, ultraviolet–visible spectrophotometry, photoluminescence and Hall measurements at room temperature. The Al contents of the L-AZO film were analyzed with secondary ion mass spectroscopy. As the Ar/0.3%H2 gas flow was increased up to 200 sccm, the transmittance and conductivity of the film simultaneously improved as a function of the increasing flow rate without additional thermal or gas treatment. The 40 nm-thick L-AZO film, which was deposited by an Ar/0.3% H2 gas flow of 200 sccm at a substrate temperature of 100 °C, had a carrier concentration of 1.0 × 1020/cm3, resistivity of 5.5 × 10− 3 Ω-cm, and an average transmittance of 93% in the wavelength range from 300 nm to 2000 nm.