InGaN nanostructures are among the most promising candidates for visible solid-state lighting and renewable energy sources. To date, there is still a lack of information about the influence of the growth conditions on the physical properties of these nanostructures. Here, we extend the study of InGaN nanowires growth directly on Si substrates by plasma-assisted molecular beam epitaxy. The results of the study showed that under appropriate growth conditions a change in the growth temperature of just 10 °C leads to a significant change in the structural and optical properties of the nanowires. InGaN nanowires with the areas containing 4%–10% of In with increasing tendency towards the top are formed at the growth temperature of 665 °C, while at the growth temperatures range of 655 °C–660 °C the spontaneously core–shell NWs are typically presented. In the latter case, the In contents in the core and the shell are about an order of magnitude different (e.g. 35% and 4% for 655 °C, respectively). The photoluminescence study of the NWs demonstrates a shift in the spectra from blue to orange in accordance with an increase of In content. Based on these results, a novel approach to the monolithic growth of In _x Ga _{1− x} N NWs with multi-colour light emission on Si substrates by setting a temperature gradient over the substrate surface is proposed.

GaN nanowires were grown using selective area plasma-assisted molecular beam epitaxy on SiO_x/Si(111) substrates patterned with microsphere lithography. For the first time, the temperature–Ga/N₂ flux ratio map was established for selective area epitaxy of GaN nanowires. It is shown that the growth selectivity for GaN nanowires without any parasitic growth on a silica mask can be obtained in a relatively narrow range of substrate temperatures and Ga/N₂ flux ratios. A model was developed that explains the selective growth range, which appeared to be highly sensitive to the growth temperature and Ga flux, as well as to the radius and pitch of the patterned pinholes. High crystal quality in the GaN nanowires was confirmed through low-temperature photoluminescence measurements.

Hybrid nanostructures based on InGaN nanowires with decorated plasmonic silver nanoparticles are investigated in the present study. It is shown that plasmonic nanoparticles induce the redistribution of room temperature photoluminescence between short-wavelength and long-wavelength peaks of InGaN nanowires. It is defined that short-wavelength maxima decreased by 20%, whereas the long-wavelength maxima increased by 19%. We attribute this phenomenon to the energy transfer and enhancement between the coalesced part of the NWs with 10–13% In content and the tips above with an In content of about 20–23%. A proposed Fröhlich resonance model for silver NPs surrounded by a medium with refractive index of 2.45 and spread 0.1 explains the enhancement effect, whereas the decreasing of the short-wavelength peak is associated with the diffusion of charge carriers between the coalesced part of the NWs and the tips above.

We demonstrate spontaneous core–shell In_xGa_1−xN nanowires exhibiting bright photoluminescence at 650 nm. The surprising effect of material separation is attributed to the periodically changing environment for single monolayer growth.

In this work, InGaN nanowires with a high In content were grown, for the first time on hybrid SiC/Si substrates and compared with InGaN nanowires grown on Si. It was shown that InGaN nanowires on SiC/Si have lower indium content (by about 10%) compared to the nanowires on Si. The results can be beneficial for studying the growth mechanisms of InGaN nanowires and creating optoelectronic devices in the visible spectral range. Keywords: InGaN, nanowires, molecular beam epitaxy, SiC/Si, morphological properties, optical properties, miscibility gap, silicon carbide on silicon