Fabrication of Bismuth Telluride Thin Films using Thermal Evaporation Technique and its Electrical Properties

Thin films have received great attention in recent years because of their extensive applications in various fields of science and technology. The studies of the electrical properties of semiconducting thin films have been primarily provoked by attractive micro-electronic device applications. Bismuth Telluride (Bi₂Te₃) is the most widely used material among the various V- VI compounds. In this study, thin films of Bi₂Te₃ were fabricated onto different substrates (i.e., glass and silica) by using thermal evaporation technique. Their structural, morphological, optical, and electrical properties were investigated using X-ray diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), Photoluminescence (PL) spectroscopy, and Source meter instrument, respectively. XRD analysis showed that the films were crystalline in nature. FESEM images showed that the films have a homogenous and compact grain surface. The optical band gap was about 2 eV for both types of film. The I-V characteristics of thin films were analysed at temperatures ranging from 30 °C to 100 °C. It was found that the film fabricated onto silica substrates showed large electrical conductivity as compared to the others. Also, the increment in electrical conductivity was observed with the temperature indicating that the prepared films have a negative temperature coefficient of resistance.