Quasi-one-dimensional III-V semiconducting nanowires attract enormous attention owing to their physical properties such as tunable direct bandgap, high surface to volume ratio, high carrier mobility, tunable structures. Hence they have  potential application in next generation electronics, sensors, photonics and photovoltaics. Understanding the details such as, atomic scale structure, local chemical stoichiometry and defects in a sub nanometer scale are inevitable when nanowires are intended for devices.

A systematic interfacial investigation on molecular beam epitaxy grown III-V based nanowires such as InAs, GaAs,^[1] in general and in particular, heterostructure nanowires of axially grown Ga_xIn_{1_x}As-InAs and InAs-InAsSb will be presented.^[2] In this work, atomic scale structural interfaces and interfacial chemical composition are analyzed using advanced aberration corrected transmission electron microscopy.  Atomic resolution high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and high resolution energy dispersive x-ray spectroscopy techniques are predominatly used for characterizing the grown nanowires. Our work demonstrates on tailoring the growth, periodicities and the stoichiometry of III-V nanowire heterostructure containing single/multiple electronic barriers involving In,Ga,As and Sb. We aim to provide understanding on the growth of dissimilar interfaces in heterostructure nanowire (see fig 1). In the InAs-InAsSb heterostructure wires,^[1] our work demonstrates the quality of the misfit strained interface in terms of structural abruptness and chemical homogeneity. 

References

1. S. Venkatesan, P. Krogstrup, C. Liebscher, G.Dehm, (Unpublished)

2. S. Venkatesan, M.H. Madsen, H. Schmid, P. Krogstrup, E. Johnson and C. Scheu, Appl. Phys. Lett. 103, 063106, (2013).

Figures:

Fig 1: (a) Overview HAADF-STEM image shows 8 of 11 GaxIn1_xAs segments in an InAs nanowire. (b) Magnified view revealing enhanced dark contrast at the GaxIn1_xAs/InAs interface. (c) Atomic resolution HAADF Zcontrast image showing the dark contrast (Ga enriched region) of the wire interface with Zinc Blende structure and the rest of the wire adopts Wurtzite phase. Growth direction is indicated by white arrows.

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EMC Abstracts - https://emc-proceedings.com/abstract/atomic-scale-characterization-on-iii-v-based-heterostructure-nanowire-interfaces/