Photoluminescence Properties of Nanocomposite Thin Films Containing Indium Oxide and Indium Nitride Quantum Dots

• Main Authors: Lyu, Yang-Ru, 呂泱儒
• Other Authors: Hsieh, Tsung-Eong
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/82781363085448760848

博士 === 國立交通大學 === 材料科學與工程學系所 === 102 === Photoluminescence (PL) properties of nanocomposite thin films containing In2O3, InOxNy and InN quantum dots (QDs) prepared by the target-attachment sputtering method are presented. Microstructures analysis revealed the fine dispersion of single crystalline semiconductor QDs embedded in the SiO2 or Si dielectric matrices of nanocomposite thin films. In order to identify the Bohr radius of In2O3 QD and its correlation with the quantum confinement effects, this study prepares the In2O3 QDs of various sizes by adjusting the sputtering power, the surface coverage ratio of pellets attached on target and the sintering condition of pellets. The PL analysis of samples observed not only an obvious blue shift but also an increase of luminescence efficiency when the size of In2O3 QD approached 1.32 nm. In conjunction with theoretical calculation, the Bohr radius of In2O3 QD was identified as 1.32 nm. Nanocomposite thin films containing In2O3 QDs with sizes greater than 1.32 nm were also prepared in order to eliminate the quantum confinement effect so that the origins of visible emissions in such samples could be analyzed. The red and blue emissions were found to correlate with the presence of donor carriers and the stoichiometry deviation of In2O3 was also found to affect the PL intensity of blue emission. This implied that the red and blue emissions are originated from the transitions of indium interstitial ( ) and oxygen vacancy ( ) defect levels, respectively. The presence of acceptor carriers affected the PL intensity of green emission, indicating such an emission is originated from the transition of indium vacancy ( ) defect level. The suppression of green emission in nanocomposite thin films containing In2O3 QDs caused by the dielectric confinement effect was observed by introducing nitrogen (N2) during the sputtering deposition of samples. This further illustrated that the correlation of green emission with indium vacancy in In2O3 since the dielectric confinement effect mainly affects the acceptor carriers at the QD surface. The introduction of N2 also led to the N-incorporation in In2O3 QDs and consequently resulted in the violet emission. The N-incorporation in In2O3 QDs was further enhanced by adopting the InN pellets for target-attachment sputtering deposition. X-ray photoemission spectroscopy (XPS) analysis revealed that the N2 atoms occupy oxygen vacancy sites of In2O3 QDs and generate a new defect type, . The implied that the transition of defect level results in the violet emission of nanocomposite thin films containing In2O3 QDs. Finally, the nanocomposite thin films containing InN QDs were prepared by the target-attachment sputtering method. The samples were able to emit the infrared (IR) emission at room temperature and the pinning effect of conduction band edge at Fermi stabilization level was observed. The pinning effect was the major cause for the absence of quantum confinement effect in bandgap (Eg) tuning of InN. In addition, the band tailing and thermal population effects was found to cause the asymmetry at low and high energy wings of PL spectra and such an asymmetry can be suppressed by reducing the measurement temperature.