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: Excitation Intensity Driven PL Shifts of SiGe Islands on Patterned and Planar Si(001) Substrates: Evidence for Ge-rich Dots in Islands | Nanoscale Res Lett 2010 5 1868-1872 DOI s11671-010-9713-z SPECIAL ISSUE ARTICLE Excitation Intensity Driven PL Shifts of SiGe Islands on Patterned and Planar Si 001 Substrates Evidence for Ge-rich Dots in Islands M. Brehm M. Grydlik F. Hackl E. Lausecker T. Fromherz G. Bauer Received 28 June 2010 Accepted 19 July 2010 Published online 5 August 2010 The Author s 2010. This article is published with open access at Abstract For randomly nucleated SiGe Si 001 islands a significantly stronger blue-shift of the PL spectra as a function of the excitation intensity is observed when compared to islands grown on patterned substrates side by side within the same run in a solid source molecular beam epitaxy chamber. We ascribe this different PL behavior to the much larger inhomogeneity of the Ge distribution in islands on planar substrates when compared to islands grown on pit-patterned ones as observed previously. 3D band-structure calculations show that Ge-rich inclusions of approximately 5 nm diameter at the apex of the islands can account for the observed differences in the PL spectra. The existence of such inclusions can be regarded as a quantum dot in an island and is in agreement with recent nanotomography experiments. Keywords SiGe Island Photoluminescence AFM Lateral ordering Intermixing Introduction Since their discovery in the early nineties 1 2 SiGe islands are regarded as promising building blocks on the road toward SiGe integrated optoelectronics 3 . In the course of understanding basic formation principles like SiGe intermixing and the influence of kinetic and thermodynamic effects during nano-structure growth the SiGe system together with the InAs on GaAs 001 system M. Brehm M. Grydlik F. Hackl E. Lausecker T. Fromherz G. Bauer Institute of Semiconductor and Solid State Physics University of Linz Altenbergerstrasse 69 4040 Linz Austria e-mail established themselves as a model system of Stranski-Krastanow .
