2014年6月27日（周五）上午10:30，物理系seminar：

报告题目： Readsorption-assisted growth of InAs/InSb heterostructured nanowire arrays 报告人： A. Li Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands 报告时间： 2014-6-27 10:30 报告地点：理科楼315 摘要： Among all III-V semiconductors, InSb has several outstanding properties such as small bandgap, high bulk electron mobility, largest Landѐ g-factor, and strong spin-orbit interaction. According to theoretical studies on thermoelectric property of III-V semiconductors, InSb is also considered to be the best choice for thermoelectric applications due to its small effective mass. In addition, InSb 1 nanowires (NWs) and InAs 2 NWs have been recently used to detect Majorana Fermions. A recent work on metalorganic vapor phase epitaxy growth of patterned InSb NWs shows that the growth rate of InSb NWs decreases with increasing NW density, in agreement with the material competition model. 3 This behavior limits the possibility to grow long and dense InSb NWs.
We overcome this issue in growth of InSb NWs with chemical beam epitaxy (CBE). As the first step, we have fabricated highly controlled InAs/InSb NW arrays with different diameter and pitch (i.e. NW density). Hexagonal gold catalyst arrays were defined by electron beam lithography (EBL). The growth of InAs/InSb NWs was achieved by CBE. Trimethylindium (TMIn), tertiarybutylarsine (TBAs), and tris-dimethylaminoantimony (TDMASb) were used as metal-organic precursors. One typical SEM image of the as-grown NW array is shown in Fig 1. From the SEM images of NWs we observe a growth rate behavior with respect to NW density opposite to the previous findings. 3 In fact we have found that InSb growth rate increases with increasing NW density. In order to explain this behavior we argue that the readsorption process must be considered as a major material supply pathway for the growth of InSb NWs (see the schematic drawing in Fig. 2 (a)). Therefore, we develop a model which includes the contribution of the readsorption of desorbed adatoms. Within this model the growth rate of InSb NW is linearly dependent on readsorption probability ω. As shown in Fig 2 (b), the model agrees well with the whole set of data. Our results provide guidelines for growing high density NW arrays with a high growth rate.
[1] Mourik, V.; Zuo, K.; Frolov, S. M.; Plissard, S. R.; Bakkers, E. P. A. M.; Kouwenhoven, L. P. Science 336, 1003 (2012)
[2] Das, A.; Ronen, Y.; Most, Y.; Oreg, Y.; Heiblum, M.; Shtrikman, H. arXiv: 1205.7073v1 [cond-mat.mes-hall] (2012)
[3] Plissard, S. R.; Slapak, D. R.; Verheijen, M. A.; Hocevar, M.; Immink, G. W. G.; van Weperen, I.; Nadj-Perge, S.; Frolov, S. M.; Kouwenhoven, L. P.; Bakkers, E. P. A. M. Nano Lett. 12, 1794 (2012)