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1InGaN nanowires: MBE growth, physical properties and
application
V.O. Gridchin1-3*, R.R. Reznik1-3, G.E. Cirlin1-3
1-Alferov University, Saint Petersburg, Russia 2- Saint Petersburg State University, Saint Petersburg, Russia 3- Institute for Analytical Instrumentation, Saint Petersburg, Russia
Nowadays, significant research attention is focused on semiconductor nanowires (NWs). The rapid development of this field is supported by the fact that semiconductor materials in the NW structure can be synthesized with a crystalline quality that is an order of magnitude higher than the quality of the corresponding epitaxial layers and on the lattice-mismatched substrates with respect to the growing material, in particular, silicon. In this way, InGaN ternary compounds are being actively studied direct bandgap semiconductor materials, the band gap of which can be varied in the range from 0.7 to 3.4 eV by changing the indium mole fraction. Today, InGaN finds its application in advanced optoelectronic devices of visible spectral range, such as RGB micro- and nano- light emitting diodes. However, due to the significant mismatch of lattice constants between InN and GaN, InGaN towards to phase decomposition over almost the entire chemical range. In the case of epitaxial layers, this difficulty often leads to the uncontrolled formation of areas with high and low indium content and poor crystal and optical quality. But in the case of the NW growth, it is possible to fabricate novel nanoheterostructures, such as NWs with a spontaneously formed core-shell structure with a high In content in the cores [1], the study of the properties of which is of scientific and practical interest.
This work is devoted to an experimental study of the growth of InGaN NWs using plasma-assisted molecular beam epitaxy, the fabrication of nano- light emitting diodes based on the obtained NWs, and the study of the physical properties of the grown nanostructures. It has been established that InGaN NWs with a spontaneously formed core-shell structure and a high In content are formed at relatively high growth temperatures, exceeding the decomposition temperatures of InN in vacuum [2]. In this case, the In content inside NWs can be varied in the range of 30-45% by unsufficient reducing the growth temperature, which is explained by a decrease in In desorption from the growth surface. The influence of the III/V flux ratio on the formation of NWs has been studied and it has been shown that for their formation in the core-shell structure it is necessary to maintain the III/V flux ratio near 1, taking into account the desorption of In from the growth surface. A relationship was revealed between the In content, growth conditions, and optical properties of NWs. The possibility of creating nano- light emitting diode structures with a blue-green emission spectrum based on p-i-n structures consisting of GaN/InGaN NWs with bulk InGaN inserts has been demonstrated.
The results obtained can be used in the development of RGB diodes on silicon and in studying the growth processes of spontaneously formed nanoheterostructures in NWs based on ternary compounds.
The work was carried out with financial support from the Russian Science Foundation (project No. 23-79-00012).
[1] V.O. Gridchin, K.P. Kotlyar, R.R. Reznik, A.S. Dragunova, N.V. Kryzhanovskaya, V.V. Lendyashova, D.A. Kirilenko, I.P. Soshnikov, D.S. Shevchuk, G.E. Cirlin, Multi-colour light emission from InGaN nanowires monolithically grown on Si substrate by MBE, Nanotechnology, vol. 32, pp. 335604, (2021).
[2] G. Koblmuller, C. S. Gallinat, J. S. Speck, Surface kinetics and thermal instability of N-face InN grown by plasma-assisted molecular beam epitaxy, Journal of Applied Physics, vol. 101, pp. 083516, (2007).
