Anomalous defect emissions of XEOL spectra from sapphire wafers

Yung-Yang Lin^1,2*, 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, email:aa19960511@gmail.com

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