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Investigation of Ge quantum dots buried in silicon matrix by x-ray absorption
|Iraida N. Demchenko 2, Krystyna Lawniczak-Jablonska , Konstantin S. Zhuravlev 1, Edyta Piskorska|
1. Institute of semiconductor physics (ISP), Lavrentiev, Novosibirsk, Russian Federation
The physical properties of quantum confined semiconductor heterostructures have attracted wide attention both from the experimental and theoretical point of view because of their potential applications in microelectronics and development of Si-based optoelectronics. Particularly, there is a considerable interest in the improvement of the electron-hole recombination efficiency of indirect-gap semiconductors using quantum low-dimension effects. Investigation of changes in the local atomic arrangement of formed germanium quantum dots (QD) in Si/Ge/Si structures with different thickness of germanium monolayers (ML) and capped Si layer will be reported. The presence of Si covering layer on the Ge ML induces additional stresses and can, considerably, change the shape and composition of formed structures. It can also introduce local distortion of the symmetry: changes in interatomic distances and bond angles between neighbouring atoms. To get inside into structure of buried Ge the element selective technique is necessary. Knowing that the X-ray absorption spectra are very sensitive to the local order in formed structures and are sources of unique information about morphology of matter we studied the K-edge of Ge. The measurements were performed for two angles (20o and 75o) between incidence beam and samples surface. The analysis was done taking into account linear polarization of synchrotron radiation and with assumption of the solid solution GexSi1-x inside QD. The existence of the interface between QD and Si matrix introduces a chemical disorder, which consequently increases of the Debye-Waller factor value in analyzed spectra. The comparison of investigated structures with reference GexSi1-x solid solution grown on the Si (001) substrate will be discussed. This work was supported, in part by grant of the State Committee for Scientific Research (Republic of Poland) No. SPUB-M/DESY/P-03/ DZ-213/2000.
Presentation: poster at E-MRS Fall Meeting 2003, Symposium B, by Iraida N. Demchenko
See On-line Journal of E-MRS Fall Meeting 2003
Submitted: 2003-05-07 15:05 Revised: 2009-06-08 12:55