Structure and thermal stability of δ-Bi2O3 thin films deposited by reactive sputtering

Abstract

Nanocrystalline δ-Bi2O3 thin films have been deposited onto Si (100) and quartz substrates by reactive sputtering. The structural characteristics and thermal stability of the thin films have been investigated by x-ray diffraction and Raman spectra. It was found that the δ-Bi2O3 thin films could exist stably below 200 °C and undergo a phase transition sequence δ → β → α with increasing annealing temperature beyond 200 °C. These phase transitions were further confirmed by optical constant and optical band gap studies.