GROWTH OF AZO FILMS ON BUFFER LAYERS BY RF MAGNETRON SPUTTERING

Abstract

Al 2 O 3-doped zinc oxide (in AZO, the Al 2 O 3 contents are approximately 2 wt.%) films have been grown by radio frequency (RF) magnetron sputtering at room temperature under varied sputtering pressures ranging from 3.5–15 mTorr. The electrical resistivity of AZO films is about 2.22×10-3 Ωcm (sheet resistance ~ 89 Ω/square for a thickness ~ 250 nm), and the visible range transmittance is about 80% at the argon sputtering pressure of 15 mTorr and a RF power of 100 W. This study analyzes the structural, morphological, electrical and optical properties of AZO thin films grown on soda-lime glass substrate with 2, 5, and 10 nm thick Al buffer layers (and SiO 2 buffer). For the films deposited on the 2 nm thick Al buffer layer, we obtained a c-axis-oriented AZO/ Al thin film on glass with the XRD full-width at half maximum (FWHM) of 0.31 and root mean square (RMS) surface roughness of about 3.22 nm. The lowest resistivity of 9.46×10-4 Ωcm (sheet resistance ~ 37.87 Ω/square for a thickness ~ 250 nm) and a high transmittance (80%) were obtained by applying a 2 nm thick Al buffer layer. In contrast, the resistivity was slightly increased by applying the SiO 2 buffer layer.