Abstract

InP/Ga2O3 core-shell nanowires were grown on Si substrate at 400 ºC in the hydrazine (N2H4) vapor diluted with 3 mol. % H2O. The
crystalline InP and solid Ga served as source materials for the growth of nanowires. According to TEM and EDX data the nanowires
consisted of InP core with wurtzite-type structure and an amorphous Ga2O3 shell. The minimum diameter of NWs was 14 nm, while the
maximum lengths reached several micrometers. The twinned planes appeared in WZ InP core at increased nanowire diameters. Based on
the obtained results and possible chemical reactions, the following mechanism was proposed for the growth of core-shell nanowires:
pyrolytic decomposition of hydrazine caused the appearance of intermediate NH2, NH and H species in the vapor. At elevated temperatures
the crystalline InP source was also dissociated to In and phosphorus precursors. At source temperatures close to 600 ºC, due to the
interaction of In and Ga sources with water molecules and hydrazine decomposition products the volatile Ga2O and In2O were formed.
These molecules reached the Si substrate which was heated to 400 ºC. The final chemical reaction involved Ga2O3, In2O3 and phosphorus
precursors. As a result of a spontaneous reaction the Ga2O3 and InP phases were produced and segregated. The InP crystallized as a core
while Ga2O3 created the amorphous shell, because the growth temperature was insufficient for its crystallization.

Key words: core-shell nanowire, indium phosphide, gallium(III) oxide.