Nanoscale physics
Local strain distribution and electron accumulation effects in the PAMBE grown GaN nanowires with AlxGa1-xN insets 

Lytvyn P1., Nikolenko A1., Kuchuk A1., Malyuta S1., Tsykaniuk B1., Strelchuk V1., Prokopenko I1., Wierzbicka A2., Sobanska M2., Zytkiewicz Z2.
1 V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Pr. Nauky 41, 03680 Kyiv, Ukraine
2 Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland.

One dimensional electronics provides a great potential for the best performance of novel optoelectronic devices, such as high-brightness light-emitting diodes, optically pumped nanowire lasers, sensors, flexible devices, etc. The III-nitride nanowires (NWs) have excellent physical properties that could not be achieved using another material. The 1D geometry of the NWs allows to overcome the problems of strain relaxation through the generation of extended defects in 2D epitaxial heterostructures. 
However, MBE growth of complex axial NW heterostructures leads to overgrowth of their side walls, thus creating the radial core-shell structures and generating additional axial strains as well as piezo polarization and electron accumulation effects in III-N NW structures.

Fig.1. The reciprocal space maps of asymmetric 105 reflection of GaN NWs with AlxGa1-xN insets.
We report on a correlative experimental study of strains and related local electrical properties of the PAMBE-grown GaN/AlxGa1-xN/GaN NWs. The correlations between Raman, photoluminescence, high-resolution X-ray diffraction and scanning Kelvin probe force microscopy results are discussed.