In Situ Optical Monitoring and Morphological Evolution of Si Nanowires Grown on Faceted Al2O3(0001) Substrates


Toktarbaiuly O. Zhazitov M. Abdullah M. Tezekbay Y. Kydyrbay N. Nuraje N. Duisebayev T.
October 2025Multidisciplinary Digital Publishing Institute (MDPI)

Nanomaterials
2025#15Issue 20

This paper presents the growth and in situ optical characterization of silicon nanowires (Si NWs) on Al2O3(0001) substrates that are thermally faceted using the atomic low angle shadowing technique (ATLAS) method. Annealing Al2O3 substrates in air before surface faceting was used for the first time, as identified by atomic force microscopy (AFM). Planar Si NW arrays were subsequently deposited and characterized in real-time by reflectance anisotropy spectroscopy (RAS). RAS measurements detected irreversible spectral changes during growth, e.g., red-shift in peak energy for marking amorphous Si NW formation. Blue-shifts in RAS spectra following annealing post-growth at varied temperatures were found to be associated with structural nanowire development. AFM analysis following annealing detected dramatic changes in morphology, e.g., quantifiable differences in NW height and thickness and complete disappearance of nanowire structures at high temperatures. These results confirm the validity of in situ RAS as a monitoring tool for nanowire growth and illustrate Si NW morphology’s sensitivity to thermal processing.

amorphous-to-crystalline transition , catalyst-free growth , faceted sapphire substrates (Al2O3(0001)) , in situ optical monitoring , morphological evolution , reflectance anisotropy spectroscopy (RAS) , silicon nanowires (Si NWs)

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Renewable Energy Laboratory, National Laboratory Astana (NLA), Nazarbayev University, Kabanbay Batyr 53, Astana, 010000, Kazakhstan
TEQNOVATE LCD, Astana, 010000, Kazakhstan
Department of Chemical & Materials Engineering, School of Engineering & Digital Science, Nazarbayev University, Astana, 010000, Kazakhstan

Renewable Energy Laboratory
TEQNOVATE LCD
Department of Chemical & Materials Engineering

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