Low temperature hydrothermal growth and optical properties of ZnO nanorods

Abstract

Well-faceted hexagonal ZnO nanorods have been synthesized by a simple hydrothermal method at relative low temperature (90°C) without any catalysts or templates. Zinc oxide (ZnO) nanorods were grown in an aqueous solution that contained Zinc chloride and ammonia (25%). Most of the ZnO nanorods show the perfect hexagonal cross section and well-faceted top and side surfaces. The diameter of ZnO nanorods decreased with the reaction time prolonging. The samples have been characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurement. XRD pattern confirmed that the as-prepared ZnO was the single-phase wurtzite structure formation. SEM results showed that the samples were rod textures. The surface-related optical properties have been investigated by photoluminescence (PL) spectrum and Raman spectrum. Photoluminescence measurements showed each spectrum consists of a weak band ultraviolet (UV) band and a relatively broad visible light emission peak for the samples grown at different time. It has been found that the green emission in Raman measurement may be related to surface states.

Optical Analysis of Nanocrystalline ZnO Films Coated on Porous Silicon by Radio Frequency (RF) Magnetron Sputtering

“…For nanocrystalline ZnO, only the allowed Raman phonon modes of A 1 (LO) are clearly visible at 522 and 530 cm −1 for growth on porous Si(111) and Si(100) substrates, respectively. In comparison to the result obtained from Yang et al [24], which has A 1 (LO) mode of wurtzite ZnO at 534 cm −1 , it is discovered that our A 1 (LO) mode of wurtzite ZnO is turned towards lower frequency. This inconsistency can be ascribed to the quality of the nanocrystalline ZnO as well as the coupling effects between the LO and the free carrier concentrations, which are known as the LO plasmonphonon (LPP) coupling effects.…”

Oriented growth of ZnO nanostructures on different substrates via a hydrothermal method

“…In recent years, most of the reports failed to produce ZnO nanorod arrays at relatively low temperature although many of them were on the preparation of 1D ZnO nanostructures via hydrothermal methods [27,28] focused on the preparation of ZnO nanorod arrays by using different substrates, especially on the effects of the substrates on the morphologies and photoluminescence properties. Therefore, how to fabricate well aligned and oriented 1D ZnO nanorods on different substrates at low temperature with a low cost still remains a great challenge.…”

Facile morphology‐controlled hydrothermal synthesis of flower‐like self‐organized ZnO architectures

“…The interest in zinc oxide (ZnO), an important compound semiconductor, has been encouraged in recent years by its attractive properties, such as wide bandgap, large excitation binding energy, good piezoelectric characteristic, high thermal stability, and its variable structural features. Crystalline ZnO materials with different sizes and morphologies have been obtained by several kinds of synthetic methods including sol-gel process [18][19][20][21][22], coprecipitation method [23,24], physical or chemical vapour deposition [25][26][27][28][29][30], thermal evaporation [31][32][33][34][35][36][37], solvo-or hydrothermal synthesis [38][39][40][41][42][43][44][45][46], of which hydrothermal synthesis is considered as an effective way in preparing uniform and complex ZnO structured materials.…”