Phase Transformation and Optoelectronic Properties of P-type CuFeO2 Films

• Main Authors: Lee, Yu-Fu, 李昱甫
• Other Authors: Yu, Ruei-Sung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/21029434381320288399

碩士 === 亞洲大學 === 光電與通訊學系 === 103 === This study is focused on the phase change and optoelectronic properties of CuFeO2 film as p-type semiconductor. In the experiment, the film was prepared using the sol-gel method and annealed in the controlled argon atmosphere. The films were heated at 500℃~850℃, and the low-temperature phase structures of CuO, CuFe2O4, formed at 550~550℃. The increasing temperature facilitated the formation of CuFeO2. By raising the temperature, copper, iron and oxygen atoms were given enough energy to pile up and form the delafossite structure CuFeO2. The films annealing at 600℃~800℃ formed a single-phase CuFeO2 structure, and annealing at 850℃ formed a secondary-phase structure. As the annealing temperatures increased from 600℃ to 850℃, CuFeO2 had its RMS values increasing from 3.10 to 10.40 nm gradually. The surface of CuFeO2 showed a fiber-like microstructure. With the increase of the temperature, the fiber-like structure grew and thickened. The single phase CuFeO2 had direct band gaps of 3.70~3.78eV. During the Cu-Fe-O phase transformation, the change in structure determined the transmittance and absorption coefficient of the film. The CuFeO2 film absorbed mainly the photons with wavelengths smaller than 400 nm. In analysis based on the Hall effect measurement, the film exhibited hole conduction and thus was identified as p-type film. The optimum electrical properties were identified in the CuFeO2 film annealed at 700℃. The film had its carrier concentration, Hall coefficient, and resistivity measured as 3.753x 1016 cm-3, 1.665 x 102 cm3/C, and 1.196 ohm-cm, respectively.