Bismuth Oxide Thin Films for Optoelectronic and Humidity Sensing Applications

Abstract

Bismuth oxide thin films still prove attractive to both scientists and engineers due to their semiconducting behavior, large energy bandgap and high refractive index, despite their often complex structure, both polymorphic and polycrystalline. We present here a summary and a comparison of the morpho-structural and optical properties of such films prepared through three physical vapor deposition (PVD) techniques on several types of substrates kept at different temperatures. Thermal vapor deposition, thermal oxidation in air and pulsed laser deposition are discussed as largely used PVD methods. It is proved that the physical properties of the bismuth oxide thin films can be tailored by changing the substrate nature and its temperature during the deposition process in a way even more relevant than even the chosen deposition method. Thus, bismuth oxide thin films with energy bandgaps ranging from the infrared up to near-ultraviolet can be obtained, depending on their structure and morphology. High refractive index of the films can be also attained for specific spectral ranges. When deposited on certain conductive substrates, the films have much lower electrical resistance and even became sensitive to water vapor. Therefore, humidity sensing and optoelectronic applications of the analyzed bismuth oxide thin films can be easily found and used in both science and technology.

The Role of Annealing Treatment on Crystallographic, Optical, and Electrical Features of Bi2O3 Thin Films Prepared Using Reactive Plasma Sputtering Technology

“…Te same is true with nanostructures because they are optical and electrical, including their wide energy band gap, the dielectric permittivity refractive index, Bi 2 O 3 , impressive photoluminescence, photoconductivity optoelectronics, gas sensors, Schottky barrier optical coatings, and metal-insulator-semiconductor capacitors. Furthermore, solar cells and microwaves are also integrated into the circuits [1][2][3][4][5][6][7][8][9][10][11]. Generally, physical [12,13], and chemical [14][15][16], and electrodeposition methods [17] were developed for preparing diferent bismuth nanostructures like nanoparticles [16], triangular nanoplate [18], nanotubes [19,20], nanowires [21], and nanospheres [22].…”