Study of the structure and optical properties of nanocrystalline zirconium oxide thin films deposited at low temperatures

Abstract

Zirconium oxide thin films are deposited at low temperatures (lower than 350°C) using a filtered cathodic vacuum arc. Film structure, surface morphology and optical properties are systematically investigated. The results show the dependence of the properties on substrate temperature. Film structure develops from amorphous to polycrystalline at 150°C. Further increasing the temperature to 230°C leads to the preferred orientation along [−111] and [−221] directions, and at 330°C along only one observed preferred [−111] direction. In addition, crystal size in all the crystallized films is within 15 nm. The increase of substrate temperature results in an increase of surface roughness from room temperature to 230°C, but to a slight decrease at 330°C. The variations in optical properties, such as optical constants and Eg, with substrate temperature are correlated to the changes in film microstructure.

Effect of annealing on pulsed laser deposited zirconium oxide thin films

“…The root-mean-square roughness (R rms ) of the films is given in Table 1. The surface roughness is attributed to grain growth [7] and followed the same trend as the crystallite size.…”

“…They have a tetragonal structure when annealed at 400-500 • C, and a monoclinic phase when annealed at temperatures higher than 700 • C [9,23]. On the other hand, films deposited by DC reactive sputtering [2] or filtered cathodic vacuum arc [7] had a monoclinic structure.…”

“…The dominance of the monoclinic phase can be understood on the basis of the thermodynamics of crystal growth. Generally, the crystal plane with the lowest Gibbs free energy will grow preferentially [7]. In ZrO 2 , this plane corresponds to the monoclinic (1 1 1) orientation [7].…”

“…Zirconium oxide thin films have been prepared by a variety of techniques including ion-beam assisted deposition [1], sputtering [2,3,5], cathodic arc deposition [4,6,7], sol-gel [8][9][10][11], atomic layer deposition [12], and thermal oxidation of zirconium [13]. ZrO 2 thin films have been fabricated by pulsed laser deposition (PLD) mostly using the ultraviolet krypton fluoride (KrF) excimer laser.…”

Study of nanocluster‐assembled ZnO thin films by nanocluster‐beam deposition

“…The nanocrystal size obtained by XRD is similar to that observed by previous TEM study. During the film growth with on-line heating provided, it tends to form crystallites with good structure induced by thermodynamics factors [16]. From published data, under the high growth temperature, ZnO thin films normally exhibit three sharp XRD peaks corresponding to the planes of (100), (002) and (101) [17][18][19].…”