Structural, morphological, and optical properties of Bi2O3 thin films grown by reactive sputtering

• DOI: 10.1016/j.tsf.2017.01.013
• Publication Date: 2017-01-10T18:03:43Z
• Authors: P. Lunca Popa; S. Sønderby; S. Kerdsongpanya; J. Lu; H. Arwin; P. Eklund
• Keywords: Bismuth oxide; Reactive sputtering; Phase transition; Materials Chemistry; Materialkemi; 01 natural sciences; 0104 chemical sciences

Abstract Bi 2 O 3 thin films were grown using reactive RF sputtering from a metallic Bi target. The influence of various deposition parameters (substrate temperature, applied power on target and oxygen content in the working gas) on the morphology, structure and optical properties of films was investigated. Depending on the O 2 /(Ar + O 2 ) ratio of the working gas, bismuth, δ-Bi 2 O 3 , α-Bi 2 O 3 or a mixture of these phases can be deposited, with a narrow window for growth of [111]-oriented δ-Bi 2 O 3 thin films. The δ-Bi 2 O 3 phase is stable from room temperature up to 350 °C (in air), where an irreversible transition to α-Bi 2 O 3 occurs. This phase transformation is also shown to occur during TEM sample preparation, because of the inherent heating from the ion-milling process, unless liquid-nitrogen cooling is used.