Anomalous defect emissions of XEOL spectra from sapphire wafers
Yung-Yang Lin1,2*, Song Yang1, Yu-Hao Wu1, Shih-Yu Fu1, Chien-Yu Lee1, Bo-Yi Chen1, Gung-Chian Yin1, Bi-Hsuan Lin1, Chia-Hung Hsu1, Mau-Tsu Tang1
1National Synchrotron Radiation Research Center, Hsinchu, Taiwan
2National Tsing Hua University, Hsinchu, Taiwan
* Presenter:Yung-Yang Lin,
The features of TPS 23A X-ray nanobeam operating in hybrid bunch mode can provide not only a sufficiently high peak power density but also high-quality temporal domain measurements for studying the luminescence dynamics of materials. Based on the advantages, the emission properties of c-, a-, r- and m-plane sapphire wafers have been studied using X-ray excited optical luminescence (XEOL) with nano-focused X-ray beams. We observed clearly the well-known sapphire defect emissions, a broad emission at 330 nm and a sharp emission at around 700 nm, which were attributed to F+ center and Cr3+ impurities, respectively. However, the F+ center emission exhibited a anomalous behavior that the emission intensity increased with X-ray irradiation time. This behavior was only influenced by X-ray peak power density, regardless of X-ray energy. When the peak power density was lowered using an attenuator, the intensity of F+ center no longer increased with X-ray irradiation time. Detailed results of the experiemnts will be reported.

Keywords: XEOL, sapphire, defect emission