Growth and characterisation of GaAs/InGaAs/GaAs nanowhiskers on (1 1 1) GaAs

doi:10.1016/j.jcrysgro.2006.10.122

Journal of Crystal Growth

Volume 298, January 2007, Pages 607-611

https://doi.org/10.1016/j.jcrysgro.2006.10.122 Get rights and content

Abstract

GaAs/In_xGa₁₋_xAs/GaAs heterostructures nanowires were grown by metal-organic vapor-phase epitaxy on (1 1 1)B GaAs substrate using the vapor–liquid–solid growth mode. The diameter of the nanowires was defined by monodisperse gold nanoparticles deposited on the GaAs substrate. High-resolution electron transmission microscopy investigation revealed the structural properties of the grown whiskers using bright field images. Using energy disperse X-ray spectroscopy measurements, the composition along and perpendicular to the vertical growth direction has been determined. In addition, the sharpness of the created heterojunctions was investigated. Finally, micro photoluminescence measurements on single GaAs/InGaAs/GaAs whiskers were carried out.

Introduction

Semiconductor nanowhiskers excite a great research interest due to their intriguing growth features as well as a potential application in nanoscale electronic and optoelectronic devices. Based on the vapour–liquid–solid (VLS) growth mechanism [1] using Au seed particles or templates various semiconductor nanowhiskers have been reported. Shrinking the Au seed to the nanometer scale and using the metal-organic vapor phase epitaxy technique [2] enabled the realization of highly mismatched one-dimensional semiconductor heterostructures [3], [4]. Despite a good progress in the growth of elementary and binary materials, there is a lack of studies on ternary compounds and their heterointerfaces. The change of group-III elements was only published once in 1994 by forming a heterojunction between GaAs and InAs along the vertical growth direction [5]. These structures are indispensable for band gap engineered devices i.e. for III/V-based optoelectronics at 1.3/1.55 μm on a Si substrate [6], [7]. However, the VLS growth takes place at low temperatures, which may result in a non-linear dependence of the precursor cracking and different incorporation efficiency in the whisker. In addition, the range of growth temperature variation is further limited by potential whisker kinking [8] and parasitic 2-dimensional growth.

In this contribution, we report the growth of high-quality GaAs/In_xGa₁₋_xAs/GaAs heterostructures on (1 1 1)B GaAs substrate. We have developed a growth temperature sequence, which enables both the incorporation of a full set of In-compositions as well as wire-kinking-free heterointerfaces. This approach became feasible by means of two different gallium precursors with different incorporation efficiencies adapted to the required growth condition. The structure and the lattice parameter of the grown structures were determined by high-resolution transmission microscopy (HR-TEM) measurements using bright-field images. The composition at the different whisker regions was analyzed using energy disperse X-ray spectroscopy (EDS) as well as micro-photoluminescence (μ-PL).

Section snippets

Experimental procedure

Growth experiments were preformed in a low-pressure MOVPE using an AIX200 RF low-pressure system with a full non-gaseous source configuration [9]. N₂ was used as carrier gas and tertiarybuthylarsine (TBAs) as group-V precursor. Trimethylindium (TMIn) was used as In precursor while both trimethylgallium (TMGa) and triethylgallium (TEGa) were used as Ga precursors. As a growth seed Au nanoparticles in a colloidal solution deposited on the substrate surface prior to the growth were used. The mean

Results

In a first step In_xGa₁₋_xAs nanowhiskers with various homogenous In-compostions x were grown. The TMIn/(TMIn+TEGa) ratio was varied from 0.038 to 0.452. The TMIn supply was changed resulting in the significant increase of a total TMIn+TEGa gas flow and consequently in a higher growth rate for In-rich structures. Fig. 1a shows XRD rocking curves of fabricated structures. The whisker peaks and the 2-dimensional In_xGa₁₋_xAs layer peaks can be clearly resolved. Depending on the chosen

Conclusion

GaAs/In_xGa_1−xAs/GaAs heterostructures nanowhisker grown in the VLS mode exhibit in a wide temperature range both lateral and vertical heterojunctions, respectively. The properties of the vertical junction in the direction of whisker growth are defined by the VLS growth mode. By means of EDS line scans no sharp InGaAs/GaAs heterojunctions were found in the vertical direction attributed to a memory effect of the group-III species in the Au droplet. The lateral heterojunctions of the core-shell

Acknowledgments

The authors acknowledge financial support of the Sonderforschungsbereich SFB 445.

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Growth and characterisation of GaAs/InGaAs/GaAs nanowhiskers on (1 1 1) GaAs

Abstract

Introduction

Section snippets

Experimental procedure

Results

Conclusion

Acknowledgments

J. Crystal Growth

Appl. Phys. Lett.

Appl. Phys. Lett.

Nano Lett.

Appl. Phys. Lett.