Template-assisted In(Ga)As Nanowires and Crosses by MBE

Martin Friedl¹, Kris Cerveny², Pirmin Weigele², Sara Martí-Sánchez³, Taras Patlatiuk2, Simon Escobar Steinvall¹, Lucas Güniat¹, Wonjong Kim¹, Jordi Arbiol^3,4, Dominik Zumbuhl², Anna Fontcuberta i Morral¹

¹ Laboratoire des Matériaux Semiconducteurs, École Polytechnique Fédérale de Lausanne, EPFL, 1015 Lausanne, Switzerland
² Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
³ Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain
⁴ ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Catalonia, Spain

Quasi-1D nanowire (NW) branches are very interesting structures being investigated for applications in coherent quantum transport and topological quantum computing. There are, however, significant material science challenges in growing structures that should have defect-free junctions, while at the same time being easily scalable and ideally compatible with traditional CMOS-based fabrication.

In this work we explore the molecular beam epitaxy (MBE) growth of In(Ga)As NWs on top of defect-free GaAs nanomembranes (NMs) to obtain laterally-oriented In(Ga)As NWs as depicted in Fig 1a. Through transmission electron microscopy (TEM) studies (as seen in Fig 1b), it was seen that the GaAs NM templates allow us to obtain very high-quality In(Ga)As NWs with few defects, despite the large lattice mismatch. This gold-free approach to NW growth is therefore very appealing as a scalable method to grow directional and position-defined NWs while having the additional advantage of being able to produce multi-branched NWs by growing them along equivalent crystalline directions.

The properties of the resulting single NWs were further explored by various methods, including high-resolution scanning transmission electron microscopy (HR-STEM), energy-dispersive X-ray spectroscopy (EDX) and magnetoconductance measurements. Our results show that NWs grown by this method exhibit quasi-1D conduction, making such a growth method interesting to explore for quantum transport experiments as well as topological quantum computing.