Preparation And Properties Of ZnSe Semiconductor By Hydrothermal Method

As an important wide band-gap Ⅱ-Ⅵ semiconductor, ZnSe has attracted much attention for their various applications in photoelectronic deⅥces such as blue light-emitting diodes and blue-green diode lasers. In this work, ZnSe powders were prepared at 100~200癈 for 12~36h by hydrothermal method with Zn, Se dissolved in NaOH aqueous solution as source materials. The cross experiment design was used in this study. The influences of processing parameters such as concentration of Zn, molar ratio of Se:NaOH, hydrothermal temperature and soaking time on the grain size, morphology and optical properties of the ZnSe powders were researched. XRD, EDAX, XPS, SEM and laser particle sizer were used to characterize the structure, composition, morphology and particle size of the samples. Optical absorption spectra of the ZnSe powders were measured by UV-ⅥS-NIR spectrometer. The powders were cubic blende ZnSe, and sufficient H2 reducing atmosphere was necessary to prepare pure ZnSe. The grain size of the ZnSe powders decreased with the increasing Zn concentration and the molar ratio of Se:NaOH, and increased with the increasing hydrothermal temperature and soaking time. The absorption edge of the ZnSe prepared at different hydrothermal conditions was 449.3~456.2nm, and shifted to higher energies due to the quantum confinement effects induced by the decrease of the grain size of the ZnSe. Superfine ZnSe nanocrystals as well as large ball-like ZnSe particles in several microns were observed in the samples. The generation mechanism of the ZnSe prepared by hydrothermal method included the dissolⅥng of Zn and Se in NaOH and then ZnSe nuclei and growth in the hydrothermal solution. Based on the mechanism, we believed that the ball-like ZnSe particles were formed by the absorption nuclei and growth of ZnSe on the surface of Zn particles, so the particle size depended on the size of the Zn powders. While the small ZnSe nanocrystals were generated by the free growth of ZnSe nuclei in the hydrothermal solution, so the grain size distribution of the ZnSe nanocrystals was narrow.