Abstract
The VLS (vapor-liquid-solid) method is one of the promising techniques for growing vertical III-V compound semiconductor nanowires on Si for application to optoelectronic circuits. Heterostructures grown in the axial direction by the VLS method and in the radial direction by the general layer-by-layer growth method make it possible to fabricate complicated and functional three-dimensional structures in a bottom-up manner. We can grow some vertical heterostructure nanopillars with flat tops on Si(111) substrates, and we have obtained core-multishell Ga(In)P/GaAs/GaP nanowires with flat tops and their air-gap structures by using selective wet etching. Simulations indicate that a high-<svg style="vertical-align:-1.90608pt;width:12.325px;" id="M1" height="12.925" version="1.1" viewBox="0 0 12.325 12.925" width="12.325" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,12.925)"> <g transform="translate(72,-61.66)"> <text transform="matrix(1,0,0,-1,-71.95,63.61)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑄</tspan> </text> </g> </g> </svg> factor of over 2000 can be achieved for this air-gap structure. From the GaAs growth experiments, we found that zincblende GaAs without any stacking faults can be grown after the GaP nanowire growth. Pillars containing a quantum dot and without stacking faults can be grown by using this method. We can also obtain flat-top pillars without removing the Au catalysts when using small Au particles.
Highlights
Free-standing nanowires are promising for future nanoscale devices
We show that zincblende GaAs can be formed over GaP nanowires without any stacking faults, which will lead to refined heterostructures and band engineering
The TEM sample of the coremultishell GaP/GaAs/GaP nanowires was thinned to about 100 nm by using the FIB method
Summary
Free-standing nanowires are promising for future nanoscale devices. The VLS growth method enables us to make quantum structures in nanowires, which will contribute to the development of nanodevices such as transistors [1], nanolasers [2], and nanosensors [3]. After the encouraging studies on lightemitting diodes using nanowires by Hiruma et al in the 1990s [5], many studies of semiconductor nanowires aiming at the production of functional devices have been reported. VLS growth is suited for application to Sibased optoelectronic integrated circuits (OEICs) because it enables to connect various III-V materials and is performed at low temperature. As already demonstrated by several groups, vertical GaP nanowires can be grown on Si(111)
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