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Báo cáo hóa học: " Defect Characterization in SiGe/SOI Epitaxial Semiconductors by Positron Annihilation"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Defect Characterization in SiGe/SOI Epitaxial Semiconductors by Positron Annihilation | Nanoscale Res Lett 2010 5 1942-1947 DOI 10.1007 s11671-010-9818-4 SPECIAL ISSUE ARTICLE Defect Characterization in SiGe SOI Epitaxial Semiconductors by Positron Annihilation R. Ferragut A. Calloni A. Dupasquier G. Isella Received 2 July 2010 Accepted 22 September 2010 Published online 24 October 2010 The Author s 2010. This article is published with open access at Springerlink.com Abstract The potential of positron annihilation spectroscopy PAS for defect characterization at the atomic scale in semiconductors has been demonstrated in thin multilayer structures of SiGe 50 nm grown on UTB ultra-thin body SOI silicon-on-insulator . A slow positron beam was used to probe the defect profile. The SiO2 Si interface in the UTB-SOI was well characterized and a good estimation of its depth has been obtained. The chemical analysis indicates that the interface does not contain defects but only strongly localized charged centers. In order to promote the relaxation the samples have been submitted to a post-growth annealing treatment in vacuum. After this treatment it was possible to observe the modifications of the defect structure of the relaxed film. Chemical analysis of the SiGe layers suggests a prevalent trapping site surrounded by germanium atoms presumably Si vacancies associated with misfit dislocations and threading dislocations in the SiGe films. Keywords Positron annihilation spectroscopy Ultrathin body films SiGe semiconductors Point defects Introduction Silicon-germanium SiGe has gained much attention in recent years thanks to its promising electrical and material properties. The complete solubility of the two elements enables band gap engineering and SiGe is relatively easy to integrate into silicon technology. There are however R. Ferragut A. Calloni A. Dupasquier G. Isella L-NESS Dipartimento di Fisica Politecnico di Milano via Anzani 42 22100 Como Italy e-mail rafael.ferragut@polimi.it still numerous issues regarding the electrical and material properties of .