Growth of wurtzite GaP in InP/GaP core–shell nanowires by selective-area MOVPE

Abstract

A GaP nanowire is promising from the viewpoint of device applications because when its crystal phase is changed from zinc blende (ZB) to wurtzite (WZ), its band gap changes from indirect to direct. GaP in the WZ phase is theoretically and experimentally shown to have the possibility of "green" emission. Here we report on the growth of WZ GaP in InP/GaP core-shell nanowires by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE). WZ InP nanowires were used as a template for transferring the WZ structure to GaP. Transmission electron microscopy revealed that WZ GaP was grown on the sidewalls of the InP core in the lateral <-211> direction and that ZB GaP was grown on the top of the InP core in the axial <111>A direction. A growth model for the different crystal structures of the GaP shell is proposed from the viewpoint of the growth direction. The WZ structure is "transferred" from the InP core to the GaP shell only when GaP grows in the direction perpendicular to the WZ stacking direction of the InP core. This so-called "crystal structure transfer" can also be applied to p-and n-doped GaP and is therefore promising for fabricating WZ-GaP-based light-emitting diodes.

Synthesis and Applications of III–V Nanowires

“…To avoid the radial growth, it is, however, also possible to use the TASE technique, described previously, where the oxide tube protects the NWs sidewalls from deposition. 131 Core−shell heterostructures have been used for surface passivation, 132 core to shell crystal structure transfer, 133 nanotube formation, 134 and to form active layers inside NW transistor devices. 135 2.1.3.3.…”

A New Strategy for Selective Area Growth of Highly Uniform InGaAs/InP Multiple Quantum Well Nanowire Arrays for Optoelectronic Device Applications

“…When InGaAs layer is grown on WZ InP nanowire core, the radial InGaAs layer could adopt WZ structure from the core due to the already fixed “ABAB…” stacking sequence. [ 29 ] However, axial InGaAs layer tends to form a more thermodynamically favorable ZB structure since growth along the axial direction is free from the constraints from the core. As the ZB InGaAs layer prefers lower‐energy {110} facets, which is rotated 30° with respect to the {} faceted InP nanowire core, complicated morphology transition occurs to minimize the formation energy for the whole nanowire.…”

Ultra-thin films for plasmonics: a technology overview

“…The main advantage of these films is the growth methods. Thus, highly doped semiconductors are generally grown using epitaxial methods like molecular beam epitaxy [135,137], metal-organic chemical vapor deposition [141], or metal-organic vapor phase epitaxy [142,143]. These techniques allow for atomically smooth layers, greatly reducing the influence of roughness in the devices.…”