Roughness evolution in Ga doped ZnO films deposited by pulsed laser deposition

• Published in: Thin solid films Vol. 519; no. 16; pp. 5444 - 5449
• Main Authors: Liu, Yun-yan, Cheng, Chuan-fu, Yang, Shan-ying, Song, Hong-sheng, Wei, Gong-xiang, Xue, Cheng-shan, Wang, Yong-zai
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2011; Elsevier
• Subjects: Atomic force microscopy; Condensed matter: structure, mechanical and thermal properties; Correlation; Cross-disciplinary physics: materials science; rheology; Deposition; Evolution; Exact sciences and technology; Fractals; Ga doped ZnO; Gallium; Laser deposition; Materials science; Mathematical models; Methods of deposition of films and coatings; film growth and epitaxy; Morphology; Physics; Pulsed laser deposition; Roughness; Structure and morphology; thickness; Surface roughness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thin film structure and morphology; Atomic force microscopy; Pulsed laser deposition; Surface roughness; Fractals; Ga doped ZnO; Morphology; Fluctuations; Surface morphology; Laser deposition; Roughness; Correlation functions; Gallium additions; Thin films; Interfaces; Growth mechanism; Zinc oxide; Laser ablation technique
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.02.056

We analyze the morphology evolution of the Ga doped ZnO(GZO) films deposited on quartz substrates by a laser deposition system. The surface morphologies of the film samples grown with different times are measured by the atomic force microscope, and they are analyzed quantitatively by using the image data. In the initial stage of the growth time shorter than 8min, our analysis shows that the GZO surface morphologies are influenced by such factors as the random fluctuations, the smoothening effects in the deposition, the lateral strain and the substrate. The interface width uw(t) and the lateral correlation length ξ(t) at first decrease with deposition time t. For the growth time larger than 8min, w(t) and ξ(t) increase with time and it indicates the roughening of the surface and the surface morphology exhibits the fractal characteristics. By fitting data of the roughness w(t) versus deposition time t larger than 4min to the power-law function, we obtain the growth exponent β is 0.3; and by the height–height correlation functions of the samples to that of the self-affine fractal model, we obtain the value of roughness exponent α about 0.84 for all samples with different growth time t.