ZnO:Ga Thin Films Produced by RF Sputtering at Room Temperature: Effect of the Power Density

Abstract

Ga-doped polycrystalline zinc oxide (GZO) thin films have been deposited at high growth rates by rf magnetron sputtering. The dependence of electrical, optical and morphological properties on the rf power density were investigated. The lowest resistivity of 1.9×10 -4 cm was obtained for a rf power density of 9 W/cm 2 and an argon sputtering pressure of 0.15 Pa at room temperature. The films are polycrystalline with a hexagonal structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The films present an overall transmittance in the visible spectra of about 85%. The low resistivity, accomplished with a high growth rate deposited at room temperature, enables the deposition of these films onto polymeric substrates for flexible optoelectronic devices and displays.

Effect of film thickness on the structural and electrical properties of Ga-doped ZnO thin films prepared on glass and Al2O3 (0001) substrates by RF magnetron sputtering method

“…12 Furthermore, Ga is less reactive and more resistant to oxidation than Al. 1,13 For the preparation of Ga-doped ZnO (GZO) films, several techniques have been utilized such as RF magnetron sputtering, 11,14 chemical vapor deposition, 15 spray pyrolysis, 16 pulsed laser deposition, 17 and molecular beam epitaxy 18 on various types of substrate such as glass, 17,19,20 Si, 21 and Al 2 O 3 . 2,22,23 Among these, the sputtering method has several advantages such as high deposition rate, good adhesion, large-scale good uniformity, low cost, safety, and easily controlled physical (structural and electrical) properties of GZO films by adjusting several parameters such as doping concentration, film thickness, processing pressure, substrate temperate, and substrate type.…”

The effect of processing parameters on the properties of Ga-doped ZnO thin films by RF magnetron sputtering

“…From Fig. 1b, the diffraction peaks became sharper and their intensity was enhanced with increasing RF power, while their location did not changes significantly, indicating that the crystal quality improved due to larger grain size which is caused more sputtering particles [11]. Fig.…”

“…2b shows that GZO films grown with different RF power have the electrical charge carrier concentration, mobility, and resistivity values in ranging from 3.6 Â 10 20 to 5.54 Â 10 20 cm À3 and from 24.26 to 26.14 cm 2 V À1 S À1 , and from 4.45 Â 10 À4 to 7.0 Â 10 À4 Xcm, respectively. The electrical properties of GZO films are improved up to RF power of 200 W, which is attributed to the improved crystal quality and reduced grain boundary scattering for charge carriers in GZO films with increasing RF power [11]. GZO films grown with different Ar working pressures show the electrical charge carrier concentration, mobility, and resistivity values ranging from 7.1 Â 10 20 to 8.36 Â 10 20 cm À3 and from 21.04 to 21.91 cm 2 V À1 S À1 , and from 3.14 Â 10 À4 to 4.12 Â 10 À4 Xcm, respectively (Fig.…”

Zinc Oxide Thin Film Morphology as Function of Substrate Position During Sputtering Process

“…In these TCO layers, for photovoltaic applications, improving conductivity of the film, while maintaining maximum transparency in the concerned part of the solar spectrum can allow optimization of the performance and efficiency of solar cells. [1] This is currently one of the main challenges that TCO research has taken on in order to achieve a conversion efficiency allowing the development of new cell technologies and thus offer an alternative to silicon cells with traditional electrodes. Various solutions are currently studied.…”