Tailorable synthesis of III-V semiconductor heterostructures in nanowires (NWs) enables new approaches with respect to designing photonic and electronic devices at the nanoscale. We present a comprehensive study of highly controllable self-catalyzed growth of gallium phosphide (GaP) NWs on template-free silicon (111) substrates by molecular beam epitaxy. We report the approach to form the silicon oxide layer, which reproducibly provides a high yield of vertical GaP NWs and control over the NW surface density without a pre-patterned growth mask. Above that, we present the strategy for controlling both GaP NW length and diameter independently in single- or two-staged self-catalyzed growth. The proposed approach can be extended to other III-V NWs.

Controlled growth of heterostructured nanowires and mechanisms of their formation have been actively studied during the last decades due to perspectives of their implementation. Here, we report on the self-catalyzed growth of axially heterostructured GaPN/GaP nanowires on Si(111) by plasma-assisted molecular beam epitaxy. Nanowire composition and structural properties were examined by means of Raman microspectroscopy and transmission electron microscopy. To study the optical properties of the synthesized nanoheterostructures, the nanowire array was embedded into the silicone rubber membrane and further released from the growth substrate. The reported approach allows us to study the nanowire optical properties avoiding the response from the parasitically grown island layer. Photoluminescence and Raman studies reveal different nitrogen content in nanowires and parasitic island layer. The effect is discussed in terms of the difference in vapor solid and vapor liquid solid growth mechanisms. Photoluminescence studies at low temperature (5K) demonstrate the transition to the quasi-direct gap in the nanowires typical for diluted nitrides with low N-content. The bright room temperature photoluminescent response demonstrates the potential application of nanowire/polymer matrix in flexible optoelectronic devices.

Control and analysis of the crystal phase in semiconductor nanowires are of high importance due to the new possibilities for strain and band gap engineering for advanced nanoelectronic and nanophotonic devices. In this letter, we report the growth of the self-catalyzed GaP nanowires with a high concentration of wurtzite phase by molecular beam epitaxy on Si (111) and investigate their crystallinity. Varying the growth temperature and V/III flux ratio, we obtained wurtzite polytype segments with thicknesses in the range from several tens to 500 nm, which demonstrates the high potential of the phase bandgap engineering with highly crystalline self-catalyzed phosphide nanowires. The formation of rotational twins and wurtzite polymorph in vertical nanowires was observed through complex approach based on transmission electron microscopy, powder X-ray diffraction, and reciprocal space mapping. The phase composition, volume fraction of the crystalline phases, and wurtzite GaP lattice parameters were analyzed for the nanowires detached from the substrate. It is shown that the wurtzite phase formation occurs only in the vertically-oriented nanowires during vapor-liquid-solid growth, while the wurtzite phase is absent in GaP islands parasitically grown via the vapor-solid mechanism. The proposed approach can be used for the quantitative evaluation of the mean volume fraction of polytypic phase segments in heterostructured nanowires that are highly desirable for the optimization of growth technologies.

In this work, oriented arrays of InAs nanowires (NWs) and InAs/InP core-shell nanoheterostructures based on NWs synthesized by molecular beam epitaxy were studied. A high surface density of NWs in the array was demonstrated (5–10 NW/μm²). High-resolution transmission electron microscopy data showed that with shell thicknesses up to 15–20 nm, pseudomorphic growth of InP is possible on the side faces of InAs NWs and with shell thicknesses greater than 20 nm, complete relaxation of elastic stresses occurs. It was found that in radial heterostructured NWs with a thin InP shell, defects are formed only in the apex region, while no defect formation is observed at the radial heterointerface.

Progress in monolithic integration of III-V semiconductor heterostructures on silicon promotes the development of silicon-based integrated optoelectronics and cost-effective light-emitting devices and photodetectors. Here, we report on the fabrication of dual-functional light-emitting and photo-detecting heterostructures based on aluminum-free quaternary dilute nitride alloys of GaAsPN, epitaxially grown on silicon wafers, operating in the red part of the visible spectrum. The use of indirect band gap GaP cladding layers minimizes light absorption and provides an ease of fabrication technology. The low-temperature grown GaP/AlGaP seeding layer has been employed to achieve antiphase domain-free growth of GaP on Si (001) with no need in complex growth techniques such as migration enhanced epitaxy. Quaternary GaAsPN alloy layers with bandgap values, ranging from 1.94 to 1.83 eV, were grown by plasma-assisted molecular beam epitaxy at a high temperature of 540 °C, which ensures high crystallinity and reduces the number of growth defects. The influence of growth conditions on the GaAsPN alloy composition, structure and optoelectronic properties is discussed. The fabricated p-i-n mesa diodes demonstrate low leakage currents and both photocurrent response for above band gap excitation with an external quantum efficiency in the range of 30-42% and bright red interband electroluminescence at room temperature.

We demonstrate the self-catalyzed vapor–liquid–solid molecular beam epitaxy growth of InAs : Bi nanowires via Bi catalytic droplets directly on Si (111) substrates.