Growth Kinetics of Heterostructured GaP−GaAs Nanowires

Abstract

We have studied the vapor-liquid-solid (VLS) growth dynamics of GaP and GaAs in heterostructured GaP-GaAs nanowires. The wires containing multiple GaP-GaAs junctions were grown by the use of metal-organic vapor phase-epitaxy (MOVPE) on SiO(2), and the lengths of the individual sections were obtained from transmission electron microscopy. The growth kinetics has been studied as a function of temperature and the partial pressures of the precursors. We found that the growth of the GaAs sections is limited by the arsine (AsH(3)) as well as the trimethylgallium (Ga(CH(3))(3)) partial pressures, whereas the growth of GaP is a temperature-activated, phosphine(PH(3))-limited process with an activation energy of 115 +/- 6 kJ/mol. The PH(3) kinetics obeys the Hinshelwood-Langmuir mechanism, indicating that the dissociation reaction of adsorbed PH(3) into PH(2) and H on the catalytic gold surface is the rate-limiting step for the growth of GaP. In addition, we have studied the competitive thin layer growth on the sidewalls of the nanowires. Although the rate of this process is 2 orders of magnitude lower than the growth rate of the VLS mechanism, it competes with VLS growth and results in tapered nanowires at elevated temperatures.

Large Photonic Strength of Highly Tunable Resonant Nanowire Materials

“…The growth of GaP nanowires has been well characterized for various conditions and substrates. 23,24 Nanowires were grown using a metalloorganic vapor epitaxy following the method of ref 20. A combination of vapor-liquid-solid (VLS) and lateral growth processes was used to precisely tune the diameter of the wires while keeping the nanowire density fixed.…”

“…In this way the wire diameter can be changed without creating extremely long nanowires. 24 After growth, the samples were cooled down in a PH 3 containing atmosphere.…”

Transition region width of nanowire hetero- and pn-junctions grown using vapor–liquid–solid processes

“…Among several possible device configurations, the axial heterojunction and pn-junction structures are obviously advantageous, because they can be directly formed during VLS nanowire growth by a switching of the source material; hence they do not require additional junction fabrication processes. However, instead of possessing the ideal u Fax: +1-919-660-8963, E-mail: ttan@duke.edu abruptness on an atomic scale, NW heterojunctions grown via the VLS method always have graded composition transition regions with a relatively large junction width [4,5,7], i.e., a sizable fraction of the nanowire diameter. We suggest that this phenomenon is a characteristic feature of the VLS growth method.…”

“…Thus, extensive studies have been performed on the preparation, property, and growth kinetics of nanowires and nanowire structures with either hetero-or pn-junctions [1][2][3][4][5][6][7][8][9]. Nanowire heterojunction structures of various semiconductors have been fabricated, e.g., Si-Ge [3][4][5], GaAs-InAs [6] and GaP-GaAs [7,8].…”

Rational synthesis and the structure-property relationships of nanoheterostructures: a combinative study of experiments and theory

“…62 Moreover, as we have stated in section 'Recent progress in DFT modeling on the atomistic structure of NHSs', on the surface of the base nanomaterial, the reactivities of different sites (steps or facets) are different and they show distinct affinities towards the deposition of the second components. For example, Bakkers et al 63 demonstrated that in the growth process of a GaP-GaAs NHS, the rate of GaP deposition onto the tips was two orders of magnitude higher than that of the growth on the sidewall. In a practical synthetic system, if the reaction kinetics are slow or the feed amount of the precursor is limited, the second component would tend to deposit onto the most active site, whereas if large amounts of raw materials are supplied, the thermodynamic differences between the different sites would be concealed.…”