Shape Engineering of InP Nanostructures by Selective Area Epitaxy

Abstract

Greater demand for III−V nanostructures with more sophisticated geometries other than nanowires is expected because of the recent intensive investigation of nanowire networks that show great potential in all-optical logic gates, nanoelectronics, and quantum computing. Here, we demonstrate highly uniform arrays of InP nanostructures with tunable shapes, such as membrane-, prism-, and ring-like shapes, which can be simultaneously grown by selective area epitaxy. Our in-depth investigation of shape evolution confirms that the shape is essentially determined by pattern confinement and the minimization of total surface energy. After growth optimization, all of the different InP nanostructures grown under the same growth conditions show perfect wurtzite structure regardless of the geometry and strong and homogeneous photon emission. This work expands the research field in terms of producing nanostructures with the desired shapes beyond the limits of nanowires to satisfy various requirements for nanoelectronics, optoelectronics, and quantum device applications.

Understanding Shape Evolution and Phase Transition in InP Nanostructures Grown by Selective Area Epitaxy

“…Secondly, on the newly formed {111}A side facet, WZ phase InP layer starts to grow along the <111>A direction as would InP nanostructures grown on InP {111}A substrate by SAE. [4,44] Although a few faulted ZB layers are initially formed at the beginning of facet growth (Figure 3c,d), subsequent growth results in a high quality WZ phase layer. Thirdly, growth is also occurring on the {111}B side facet along the <111>B direction resulting in the formation of a thin ZB layer with high density of twins, as indicated by the white dotted arrows in Figure 3h.…”

“…The patterned substrates were loaded into a metal‐organic chemical vapor deposition (MOCVD) reactor for epitaxial growth with optimized growth conditions described in our previous work. [ 4 ] Both WZ and ZB phases are formed in our InP nanostructures, thus the crystalline facets and orientations are named using the three‐index scheme for simplicity unless specified otherwise. We first investigate InP nanostructures grown on {100} substrates since this substrate orientation has been widely used for epitaxy in the industry.…”

“…Selective area epitaxy (SAE) is widely used in synthesizing III-V semiconductor nanostructures thanks to the superior controllability of site and morphology. [1][2][3][4] In particular, III-V nanowires grown using SAE technique have achieved great success in the field of nanoelectronics, nanophotonics, and solar energy. [5][6][7] However, this 1D nanostructure still faces many challenges in terms of functionality, synthesis, assembly and fabrication process as a result of the restricted size and morphology.…”

“…[9][10][11][12][13][14][15][16][17][18][19][20] For instance, Chi et al [21] reported twin-free GaAs nanosheets which have the advantage of membranelike geometry over nanowires in realizing crystal perfection. 2D and 3D nanostructures also present superior material performance, such as enhanced light scattering and second harmonic generation in V-shaped InAs nanomembranes, [22,23] large-scale emission homogeneity of InP nanorings, InP and GaAs nanomembrane arrays, [4,24] outstanding quantum transport and electronic properties of InSb nanosheets, [25][26][27][28] and reduced piezoelectric field inside InGaN quantum wells grown on nonpolar sidewalls of GaN nanosheets. [19,29] Furthermore, the larger dimensions also make device fabrication easier.…”

“…Previously, we demonstrated SAE of highly uniform InP nanostructure arrays with pure WZ phase on InP {111}A substrates, such as nanowires, nanomembranes, nanorings. [4] In the quest for exploration of complex nanostructures, substrates of other orientations are also being investigated for growing nanostructures with desired morphology and phase. For example, Gazibegovic et al [34] demonstrated the direct formation of InSb networks on InP {100} substrates with exposed {111}B facets and their applications in quantum devices.…”