Effect of Thermal Annealing on Ga-Doped ZnO Films Prepared by Magnetron Sputtering

Abstract

In this study, Ga-doped ZnO ͑GZO͒ films deposited on a sapphire utilizing magnetron cosputtering method using ZnO and Ga 2 O 3 targets were demonstrated. The results revealed that the resistivities of the GZO films reduced by at least two orders of magnitude after the thermal annealing. The reduction in resistivity could be attributed not only to the activation of Ga dopants and to the increase of electron mobility, but also to the enlargement of the grain size that occurred as a result of thermal annealing. The resistivity of GZO films reduced from 1.4 ϫ 10 −1 to 5.3 ϫ 10 −4 ⍀ cm after the films had undergone thermal annealing in nitrogen ambience with temperature ranging from 400 to 800°C. Additionally, the GZO films exhibited semiconducting conductivity and metallic conductivity in as-deposited and annealed samples ͑Ͼ600°C͒, respectively.

Process estimation and optimized recipes of ZnO:Ga thin film characteristics for transparent electrode applications

“…When the annealing temperature is increased, the absorption edge moves to shorter wavelength and the average optical transmittance increases. The shift of absorption edge with annealing temperature is due to the increase of carrier concentration of thin films and is explained by the Burstein-Moss effect, where the conduction band becomes filled at high carrier concentration and the lowest energy states in the conduction band are blocked (Oh, Jeong, Kim, Lee, & Myoung, 2005;Sheu, Shu, Lee, Tun, & Chi, 2007). Fig.…”

A study on crystallization, optical and electrical properties of the advanced ZITO thin films using co-sputtering system

“…At lower annealing temperature (≤200 • C), the film resistivity decreased with the increment of annealing temperature. The main reason is that the crystalline grain size became larger resulted in the amount of trapping states reduced [24]. As annealing temperature was more than 200 • C, the film resistivity rapidly raised which associated with the more zinc acceptor impurities were activated to recombine with the oxygen resulted in reduction of oxygen vacancies [19,25].…”

Properties of ZnO:Ga Thin Films Deposited by dc Magnetron Sputtering: Influence of Ga-Doped Concentrations on Structural and Optical Properties

“…Numerous studies have reported the deposition of ZnO:Ga films with variation deposition techniques such as atomic layer deposition (Maeng and Park, 2013), sol-gel method (Lin et al, 2010), chemical vapour deposition (Yang et al, 2009), physical vapour deposition (Lee, 2013), pulsed laser deposition (Shin et al, 2009), magnetron sputtering (Sheu et al, 2007), DC reactive magnetron sputtering (Ma et al, 2007) and RF sputtering (Yu et al, 2005). It has been reported that the properties of ZnO:Ga thin films are dependent on the deposition methods.…”