Selective growth of ZnO nanorods by the hydrothermal technique*

Shinji Nozaki, Sachin N Sarangi, Surendra N Sahu and Kazuo Uchida

Abstract

Zinc oxide nanorods were selectively grown on engineered substrates, Ag-patterned and photoresist-patterned substrates, by the hydrothermal technique using zinc nitrate (Zn(NO₃)₂) and hexamethylenetetramine ((CH₂)₆N₄). The nanorod growth was affected by the substrate to be used. The nanorods were vertically grown on a GaN substrate but not on a Si substrate because of lattice mismatch. However, since the nanorods were grown on a thick Ag film no matter what substrate was used, a thick Ag film was deposited on a Si substrate to prepare the Ag-patterned substrate. Accordingly, the nanorods were grown only on the Ag pads. When the sizes of Ag pads were small such as 100 nm ×100 nm, one single nanorod was grown on an Ag pad. As another engineered substrate, the photoresist was patterned to prepare an array of holes on a GaN-on-sapphire substrate by e-beam lithography. When the hole size was 10 nm × 10 nm and higher, concentrations of Zn(NO₃)₂and ((CH₂)₆N₄) were employed, all holes were successfully filled with a single nanorod