Using photovoltaic effect of Hg lamp on contactless electroreflectance spectroscopy to study transition mechanism of c-plane ZnO

• Main Authors: An-hao Cheng, 鄭安皓
• Other Authors: Dong-Po Wang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/76937549745072338664

碩士 === 國立中山大學 === 物理學系研究所 === 99 === Photo reflectance（PR） and Contactless electroreflectance（CER）spectra of Zn and O-faces of a c-plane ZnO bulk have been measured at room temperature, respectively. It was found that the phase of PR is the same as that of CER for the Zn-face and they are inverted for the O-face. This indicates a polarization induced field existing in the c- plane ZnO bulk due to nonzero spontaneous polarization. In addition, a mercury lamp was focused on the ZnO sample in the CER measurements to provide a photovoltaic voltage to reduce electric field in the sample. The CER spectrum with Hg lamp is more blue-shifted and its amplitude is smaller than that without Hg lamp. Hence, the type of transitions was classified as excitonic transition. The A, B, and C excitonic transition energies were obtained by fitting experimental spectra.