Air annealing induced transformation of cubic CdSe microspheres into hexagonal nanorods and micro-pyramids

作者：Kale Rohidas B^*; Lu Shih Yuan

来源：Journal of Alloys and Compounds, 2015, 640: 504-510.

DOI：10.1016/j.jallcom.2015.04.034

• Chemical deposition
• Metal chalcogenide
• X-ray diffraction
• Scanning electron microscopy
• Optical properties

CdSe thin films have been deposited onto glass substrates using a chemical bath deposition method at relatively low temperatures (40 degrees C). The precursors used for the deposition of the thin films are cadmium nitrate hexahydrate, freshly prepared sodium selenosulfate solution and aqueous ammonia solution as a complex as well as pH adjusting reagent. In order to study the influence of air annealing on their physicochemical properties, the as-deposited CdSe thin films were further annealed at 200 degrees C and 400 degrees C for 3 h in air atmosphere. Significant changes in the morphology and photonic properties were clearly observed after the thermal annealing of the CdSe thin films. The as-deposited CdSe films grow with the cubic phase that transforms into mixed cubic and hexagonal wurtzite phase with improved crystalline quality of the films after the air annealing. Morphological observation reveals that the as-deposited thin films grow with multilayer that consists of network or mesh like structure, uniformly deposited on the glass substrate over which microspheres are uniformly distributed. After air annealing, CdSe nanorods emerged from the microspheres along with conversion of few microspheres into micro-pyramids. The UV-visible study illustrates that the as-deposited thin film shows blue shifts in its optical spectrum and the spectrum was red-shifted after annealing the CdSe thin films. The band gap of the CdSe thin films were found to be decreased after the thermal treatment.

• 出版日期2015-8-15
• 单位清华大学