Novel Growth Phenomena Observed in Axial InAs/GaAs Nanowire Heterostructures

Abstract

Gold on the move…︁ A novel growth phenomenon of axial InAs/GaAs nanowire heterostructures catalyzed by Au particles was observed. Transmission electron microscopy has determined a sequence of events: 1) Displacement of the Au particle at the end of the nanowire due to InAs clustering, 2) further InAs growth leading to sideways movement of the Au particle, and 3) eventual downward nanowire growth due to the preservation of a Au/GaAs interface (see scheme).

Tuning growth direction of catalyst-free InAs(Sb) nanowires with indium droplets

“…Time series reveal that the flat membranes form gradually; it is as if the droplets favor growth on the side facet they were initially sitting on (more information available in supporting information). The observed mechanism stands in contrast to gold catalyzed nanowires, for which flat nanowires were reported due to a downward movement of the catalyst particle [43].…”

Evolution of InAs branches in InAs∕GaAs nanowire heterostructures

“…According to our recent study 17 and Dick et al, 18 interfacial energy between the metal NPs and the semiconductor materials is the key parameter that determines the success of growing an axial NW heterostructure through the VLS mechanism. This has been clearly demonstrated in Au assisted initiation of GaAs/ InAs and InAs/ GaAs NW heterostructures, where the axial growth of GaAs on InAs NWs proceeds, 19 but axial growth of InAs on GaAs NWs does not.…”

“…In the latter case, the Au particle instead slides down the original GaAs NW by preserving a Au-GaAs interface during InAs growth. 17 This growth difference is attributed to a lower interfacial energy between Au and GaAs than between Au and InAs, and this phenomenon can have general applicability in NW heterostructures growth when the interfacial energies between NP and the NW composing materials are unequal. 17 This downward movement of Au was also observed in InP and Ge growth on GaP NWs.…”

Nature of heterointerfaces in GaAs/InAs and InAs/GaAs axial nanowire heterostructures

“…6 According to this phenomenon, the nucleation of a NW is a function of the interfacial energies between the catalyst droplet and the underlying substrate and between the catalyst droplet and the nucleating NW. [7][8][9] For axial NW heterostructures to be practically useful in device applications, it is essential to eliminate misfit dislocations at the strained heterointerface and to achieve sharp heterointerfaces. Although it is possible to eliminate misfit dislocations at the heterointerface of the axial NW heterostructures, 10 securing a sharp heterointerface has been a challenging task.…”

“…This occurs to minimize the interfacial area between the Au-alloy particle and the InAs segment. 7 Figure 3͑b͒ is the corresponding high-resolution TEM ͑HRTEM͒ image showing the InAs/GaAs interface and its FFT pattern is shown in Fig. 3͑c͒.…”