Realization of Wurtzite GaSb Using InAs Nanowire Templates

Abstract

The crystal structure of a material has a large impact on the electronic and material properties such as band alignment, bandgap energy, and surface energies. Au-seeded III-V nanowires are promising structures for exploring these effects, since for most III-V materials they readily grow in either wurtzite or zinc blende crystal structure. In III-Sb nanowires however, wurtzite crystal structure growth has proven difficult. Therefore, other methods must be developed to achieve wurtzite antimonides. For GaSb, theoretical predictions of the band structure diverge significantly, but the absence of wurtzite GaSb material has prevented any experimental verification of the properties. Having access to this material is a critical step toward clearing the uncertainty in the electronic properties, improving the theoretical band structure models and potentially opening doors toward application of this material. This work demonstrates the use of InAs wurtzite nano wires as templates for realizing GaSb wurtzite shell layers with varying thicknesses. The properties of the axial and radial heterointerfaces are studied at the atomic scale by means of aberration-corrected scanning transmission electron microscopy, revealing their sharpness and structural quality. The transport characterizations point toward a positive offset in the valence band edge of wurtzite compared to zinc blende.

Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy

“…In the same study, Namazi et al have shown that the reverse transition from GaSb to InAs has identical properties. The same InGaAs ternary material emerges at the GaSb-InAs radial heterointerface in wurtzite InAs-GaSb-InAs core-shell-shell structure [71]. In the last example we present a radial/axial zinc-blende GaSb-InAs heterostructure nanowire system, where the interfaces have been identified by atomic-resolution spectrum imaging of core-loss EELS chemical signals.…”

Unraveling electronic band structure of narrow-bandgap p–n nanojunctions in heterostructured nanowires

“…Here we exploit the capabilities of monochromated VEELS in order to study on the nanometer scale the electronic band structure of a complex heterostructure as schematically shown in Figure 1. The figure depicts the electron trajectory of the electron beam from the electron gun, passing through the monochromator and being energy-filtered by a narrow slit, and then interacting with the specimen, which in this case is a wurtzite InAs-GaSb core-shell nanowire with the shell covering half of the core and leaving a bare wurtzite InAs segment, then followed by an axial zinc-blende GaSb segment [ 10 ]. An important advantage of such a complex nanostructure is the availability of materials with known properties (on the same specimen with similar conditions, e.g.…”

“…*** Fig. 1a shows an overview HAADF-STEM image of the InAs-GaSb heterostructure nanowires which were grown by metal-organic vapor-phase epitaxy (MOVPE) as described in ref [10]. The lower segment of the nanowire is a partial radial heterostructured nanowire consisting of a wurtzite InAs core (red in Fig.…”

“…The wurtzite polytype of GaSb is a metastable phase, which does not occur in bulk. In these nanowires, GaSb is forced to grow in the wurtzite structure via the so-called crystal phase transfer method [ 10 ]. Theoretically calculated bandgap values reported for this material are contradictory [ 11 , 12 , 13 ], and bandgaps both larger and smaller than the one of zinc-blende GaSb are predicted.…”

Schottky‐Contacted High‐Performance GaSb Nanowires Photodetectors Enabled by Lead‐Free All‐Inorganic Perovskites Decoration

“…[1][2][3][4][5][6][7][8][9] Having benefited from the narrow bandgap and superior hole mobility, GaSb NWs have gained many attentions in the fields of optoelectronics and electronics in the past decades. [10][11][12][13][14][15][16][17] One of the key issues affecting the practical applications is the contact barrier between GaSb NWs and metal electrodes, which is generally dependent on the work function of the used metals. [18] However, this important barrier becomes independent of the used metals in GaSb NWs based functional devices, owing to the famous surface Fermi level pinning effect.…”