Anodization of Sputtered Titanium Films

  • PDF / 1,036,527 Bytes
  • 6 Pages / 612 x 792 pts (letter) Page_size
  • 86 Downloads / 253 Views

DOWNLOAD

REPORT


1023-JJ06-10

Anodization of Sputtered Titanium Films Deepak Dhawan1, Suresh K. Bhargava2, Wojtek Wlodarski1, and Kourosh Kalantar-zadeh1 1 Sensor Technology Laboratory, School of Electrical and Computer Engineering, RMIT University, Swanston Street, Melbourne, 3001, Australia 2 School of Applied Sciences, RMIT University, Latrobe Street, Melbourne, 3001, Australia ABSTRACT Nanoporous Ti (and TiOx) thin films were prepared by anodizing RF sputtered titanium in a 1M (NH4)2SO4 (ammonium sulphate) electrolyte solution, containing 0.5wt% (NH4)F (ammonium fluoride). Characterization of the titanium films before and after anodization was performed using scanning electron microscopy and X-ray diffraction techniques. Upon anodization, voltages in the range between 2 and 10V were applied to the samples, resulting in different nano- and microstructures. Hence, it could be clearly demonstrated that the magnitude of the applied voltage has significant impact in the formation of different surface morphologies.

INTRODUCTION Micro and nano porous thin films have received considerable attention in recent years due to their high potential for commercial and technological applications. These nano porous materials show unique functional properties that can be employed in the fabrication of electronics and optical devices [1,2,3]. In addition, they have also been extensively used as nanosized templates [4-9]. Among these materials, titanium, along with its oxide form, TiOx, has received increased interest due to its gas sensing properties [10], self-cleaning abilities [11], controllable wetting characteristics [12], photo and thermal catalytic properties [13,14] and use in solar cells [15,16]. In this work, we have investigated the formation of titanium thin films using an anodization based method. The main aim of this work was to investigate the effect of anodization voltage on the micro/nanostructures of titanium thin films.

THIN FILM DEPOSITION AND ANODIZATION Titanium thin film deposition: Titanium films of 2 µm thickness were deposited on glass substrates (2 cm × 1 cm) using a RF magnetron sputterer. Initially, the chamber of the sputterer was evacuated (10-3 Pa) and then argon gas was introduced to increase the pressure to 1.33 Pa. Two different sputtering powers were used (60 W and 120 W). Samples were heated at 100∞C for the 120 W deposition and 220∞C for the 60 W deposition. Anodization process: It was previously shown that the morphology and properties of porous titanium thin films formed using anodization depend on the magnitude of voltage applied and the anodization media [10,11,17]. The effect of applied voltage and time on the anodization process is discussed here in more detail. Anodization was conducted at room temperature using a conventional two-electrode system. A steel rod was attached to each sample with silver epoxy.

The rod and the connection area were covered with an insulating polymer, while a platinum sheet with an area of 2.5 cm2 was attached to the second rod. Anodization was conducted in 1 M (NH4F)2SO4