tailieunhanh - Báo cáo hóa học: " Optimal Growth Conditions for Selective Ge Islands Positioning on Pit-Patterned Si(001)"

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: Optimal Growth Conditions for Selective Ge Islands Positioning on Pit-Patterned Si(001) | Nanoscale Res Lett 2010 5 1873-1877 DOI s11671-010-9723-x SPECIAL ISSUE ARTICLE Optimal Growth Conditions for Selective Ge Islands Positioning on Pit-Patterned Si 001 R. Bergamaschini F. Montalenti L. Miglio Received 29 June 2010 Accepted 26 July 2010 Published online 6 August 2010 The Author s 2010. This article is published with open access at Abstract We investigate ordered nucleation of Ge islands on pit-patterned Si 001 using an original hybrid Kinetic Monte Carlo model. The method allows us to explore long time-scale evolution while using large simulation cells. We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters flux temperature pit period able to influence the growth process. The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits but not so large to induce significant Ostwald ripening is clearly demonstrated. Keywords Stranski-Krastanow growth Ge Si Patterning Kinetic Monte Carlo Introduction Ge Si 001 is often considered as the prototypical example of a system following the Stranski-Krastanow SK growth modality. The appearance of nanometric-sized coherent Ge islands 1 2 following the formation of a thin wetting layer WL attracted widespread attention in view of the possible role that islands could play in developing futuregeneration devices. Two main problems were identified soon after the first experimental evidences of islands formation were reported in the literature. On a flat Si 001 substrate indeed islands tend to nucleate randomly see . the discussion in Montalenti et al. 3 precluding the possibility of obtaining ordered arrays. Secondly under a wide range of deposition conditions a bimodal distribution of islands shallow 105 pyramids and steeper multifaceted domes 4 5 is obtained. Very interestingly better lateral ordering and size homogeneity can be achieved by growing multistacked .