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Chinese Physics, 2007, Vol. 16(9): 2764-2768    DOI: 10.1088/1009-1963/16/9/044
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES Prev   Next  

Formation mechanism of Ge nanocrystals embedded in SiO2 studied by fluorescence x-ray absorption fine structure

Yan Wen-Sheng(闫文盛),Li Zhong-Rui(李忠瑞), Sun Zhi-Hu(孙治湖), Pan Zhi-Yun(潘志云), and Wei Shi-Qiang(韦世强)
National Synchrotron Radiation Laboratory, University of Science & Technology of China, Hefei 230026, China
Abstract  This paper reports that the Ge nanocrystals embedded in SiO$_{2}$ matrix are grown on Si(100) and quartz--glass substrates, and the formation mechanism is systematically studied by using fluorescence x-ray absorption fine structure (XAFS). It is found that the formation of Ge nanocrystals strongly depends on the properties of substrate materials. In the as-prepared samples with Ge molar content of 60%, Ge atoms exist in amorphous Ge (about 36%) and GeO$_{2 }$ (about 24%) phases. At the annealing temperature of 1073 K, on the quartz--glass substrate Ge nanocrystals are generated from crystallization of amorphous Ge, rather than from the direct decomposition of GeO$_{2}$ in the as-deposited sample. However, on the Si(100) substrate, the Ge nanocrystals are generated partly from crystallization of amorphous Ge, and partly from GeO$_{2}$ phases through the permutation reaction with Si substrate. Quantitative analysis reveals that about 10% of GeO$_{2}$ in the as-prepared sample are permuted with Si wafer to form Ge nanocrystals.
Keywords:  XAFS      local structures      Ge nanocrystals  
Received:  14 July 2006      Revised:  02 February 2007      Accepted manuscript online: 
PACS:  81.16.-c (Methods of micro- and nanofabrication and processing)  
  78.70.Dm (X-ray absorption spectra)  
  78.70.En (X-ray emission spectra and fluorescence)  
  81.15.Cd (Deposition by sputtering)  
  81.40.Ef (Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization)  
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 10605024, 10375059 and 10404023) and Youth Foundation of University of Science and Technology of China (Grant No KA2310000002).

Cite this article: 

Yan Wen-Sheng(闫文盛), Li Zhong-Rui(李忠瑞), Sun Zhi-Hu(孙治湖), Pan Zhi-Yun(潘志云), and Wei Shi-Qiang(韦世强) Formation mechanism of Ge nanocrystals embedded in SiO2 studied by fluorescence x-ray absorption fine structure 2007 Chinese Physics 16 2764

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