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Structural and optical nanoscale analysis of GaN core-shell microrod arrays fabricated by combined top-down and bottom-up process on Si (111)



Sergiy Krylyuk, Marcus Muller, Gordon Schmidt, Sebastian Metzner, Peter Veit, Frank Bertram, Ratan K. Debnath, Jong Yoon Ha, Baomei Wen, Paul T. Blanchard, Alexana Roshko, Abhishek Motayed, Matthew R. King, Albert Davydov, Jurgen Christen


Large arrays of GaN core-shell microrods were fabricated on Si(111) substrates applying a combined bottom-up and top-down approach which includes inductively coupled plasma (ICP) etching of patterned GaN films grown by metal-organic vapor phase epitaxy (MOVPE) and selective overgrowth of obtained GaN/Si pillars using hydride vapor phase epitaxy (HVPE). The structural and optical properties of individual core-shell microrods have been studied with a nanometer scale spatial resolution using low-temperature cathodoluminescence spectroscopy (CL) directly performed in a scanning electron microscope (SEM) and in a scanning transmission electron microscope (STEM). SEM, TEM and CL measurements reveal the formation of distinct growth domains during the HVPE overgrowth. A high free-carrier concentration observed in the non-polar {1-100} HVPE shells is assigned to in-diffusion of silicon atoms from the substrate. In contrast, the HVPE shells directly grown on top of the c-plane of the GaN pillars reveal a lower free-carrier concentration.
Japanese Journal of Applied Physics


GaN, HVPE, core-shell, cathodoluminescence, defects
Created May 15, 2016, Updated March 15, 2017