Failure and Formation of Axial Nanowire Heterostructures in Vapor-Liquid-Solid Growth
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1058-JJ01-09
Failure and Formation of Axial Nanowire Heterostructures in Vapor-Liquid-Solid Growth Mohanchand Paladugu1, Jin Zou1,2, Ya-Nan Guo1, Graeme J. Auchterlonie2, Hannah J. Joyce3, Qiang Gao3, H. Hoe Tan3, Chennupati Jagadish3, and Yong Kim4 1 School of Engineering, The University of Queensland, Bldg 50, St. Lucia, Brisbane, 4072, Australia 2 Centre for Microscopy and Microanalysis, The University of Queensland, Bldg 74, St. Lucia, Brisbane, 4072, Australia 3 Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, The Australian National University, Building 60, Canberra, 0200, Australia 4 Department of Physics, Dong-A University, Busan, Korea, Republic of ABSTRACT To observe the axial growth behavior of InAs on GaAs nanowires, InAs was grown for different growth durations on GaAs nanowires using Au nanoparticles. Through transmission electron microscopy, we have observed the following evolution steps for the InAs growth. (1) In the initial stages of the InAs growth, InAs clusters into a wedge shape preferentially at an edge of the Au/GaAs interface by minimizing Au/InAs interfacial area; (2) with further growth of InAs, the Au particle moves sidewards and then downwards by preserving an interface with GaAs nanowire sidewalls. The lower interfacial energy of Au/GaAs than that of Au/InAs is attributed to be the reason for such Au movement. This downward movement of the Au nanoparticle later terminates when the nanoparticle encounters InAs growing radially on the GaAs nanowire sidewalls, and with further supply of In and As vapor reactants, the Au nanoparticle assists the formation of InAs branches. These observations give some insights into vapor-liquid-solid growth and the formation of kinks in nanowire heterostructures. INTRODUCTION Semiconductor nanowires and their associated heterostructures have many potential applications in nanoelectronic and nano-optoelectronic devices owing to their unique physical properties, which have drawn extensive research attention in the past decade. The growth of semiconductor nanowire heterostructures has enabled the demonstration of single nanowire devices, such as field-effect transistors, light-emitting diodes and nanowire resonant tunneling diodes.[1-2] The vapor-liquid-solid (VLS) mechanism has been a widely used mechanism for the growth of semiconductor nanowires and their heterostructures. In a typical VLS growth, metal nanoparticles are deposited on a substrate surface and heated to the growth temperature under the vapor species of growing material. Nano-sized metal liquid droplets form and, in turn, catalyze nanowire growth, so that the nanowires have metal particles at their growth front. Au nanoparticles have been widely used to catalyze the nanowire and nanowire heterostructure growth. Axial nanowire heterostructures can be grown by altering the chemical composition of vapor species during the nanowire growth and subsequent achievement of respective compositional alteration along the nanowire growth directions.[3] T
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