Influence of silicon doping on the SA-MOVPE of InAs nanowires
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Influence of silicon doping on the SA-MOVPE of InAs nanowires Kamil Sladek 1, Andreas Penz 1, Karl Weis 1, Stephan Wirths 1, Christian Volk 1, Shima Alagha 1, Masashi Akabori 2,1, Steffi Lenk 1, Martina Luysberg 3, Hans Lueth 1, Hilde Hardtdegen 1, Thomas Schaepers 1, and Detlev Gruetzmacher 1 1 Institute
of Bio- and Nanosystems (IBN-1), Forschungszentrum Juelich, Juelich, Germany.
2 Japan Advanced
Institute of Science and Technology (JAIST), Center for Nano Materials and Technology (CNMT), Nomi, Japan.
3 Institute
of Solid State Physics (IFF), Forschungszentrum Juelich, Juelich, Germany.
ABSTRACT The influence of Si-doping on the growth and material characteristics of InAs nanowires deposited by metal-organic vapor phase epitaxy (MOVPE) was investigated. It was observed that above a certain partial pressure ratio, doping has an influence on the morphology. The nanowires exhibit better uniformity but lower height vs. diameter aspect ratio as the supply of the dopant increases. It was consistantly found that the specific conductance of the nanowires also increases. Moreover the electrical measurements showed a transition from semiconducting to metallic behavior in the case of highly doped nanowires.
INTRODUCTION InAs nanowires are attractive for the realization of high-speed and low-power electronic devices due to the material‘s very high room temperature mobility [1,2]. Moreover if their lengths as well as their aspect ratios are sufficient, and if they are truly one-dimensional, they also can be applied for multi-gated nanodevices [3,4]. The wires are expected to be conductive even without doping, since the Fermi level is pinned at the surface and an electron accumulation layer should form. Nevertheless the InAs nanowires are not as conductive as they were predicted to be [5]. Reports on stacking faults [9,10] and possible material contamination due to their fabrication process may be the reason. Several methods of nanowire fabrication are established today. Two of the most common approaches are the catalyst assisted growth method [1,2,6-8] on the one hand and selective area growth mainly carried out by metalorganic vapor phase epitaxy (SA-MOVPE) on the other hand [9-11]. The latter approach, used in this contribution, implies higher material quality since no extrinsic impurities are inducible by metallic catalysts and less intrinsic impurities due to the higher and more suitable growth temperatures compared to catalyst assisted growth. Furthermore, since the position of each nanowire can be predefined, it provides control over the distribution and spacial density of the grown structures which also influences the growth behavior in selective area growth [12].
The aim of improving the conductivity of InAs nanowires leads to the question if doping can be applied without disturbing their growth and how it can affect their electronic characteristics. In this paper we therefore investigated the influence of doping on nanowire morphology and on nanowire conductivity.
EXPERIMENTAL DETAILS Growth was
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