CdSe nanorods and dendritic fractals were synthesized through a novel controllable solution-phase hydrothermal method. Soluble selenite was employed to provide a highly reactive Se source in the synthesis. Both morphologies and phases of the CdSe products could be successfully controlled by choosing appropriate complexing agents to adjust the dynamics of the reaction process. Reaction temperature and Cd/Se ratio in raw materials were also important parameters influencing the morphologies and phases of the products. The phase structures, morphologies, and optical properties of the CdSe products were investigated by XRD, TEM, HRTEM, and UV-vis and photoluminescence spectroscopies. The formation mechanisms of the nanorods and fractals were investigated and discussed on the basis of the experimental results.

Selective synthesis and characterization of CdSe nanorods and fractal nanocrystals.

With the rapid development of technologies for the fabrication of, as well as applications of low-dimensional structures, the demands on characterization techniques increase. Spatial resolution is especially crucial, where techniques for probing the properties of very small volumes, in the extreme case quantum structures, are essential. In this article we review the state-of-the-art in local probe techniques for studying the properties of nanostructures, concentrating on methods involving monitoring the properties related to photon emission. These techniques are sensitive enough to reveal the electronic structure of low-dimensional semiconductor structures and are, therefore, able to give detailed information about the geometrical structure, including fabrication-related inhomogeneities within an ensemble of structures. The local luminescence probe techniques discussed in this review article can be divided into four categories according to the excitation source: (i) spatially localized microphotoluminescence spectroscopy using either strong focusing or masking; (ii) near-field optical microscopy to reach below the diffraction limitation of far-field optics, by either exciting, detecting, or both exciting and detecting in the near field; (iii) cathodoluminescence using focused energetic electrons in an electron microscope; and (iv) scanning tunneling luminescence, using low-energy electrons injected or extracted from the tip of a scanning tunneling microscope.

Local probe techniques for luminescence studies of low-dimensional semiconductor structures

A solvothermal elemental reaction to nanocrystalline zinc selenide was proposed. The coordinating ability of the solvent was found to play an important role on the nucleation and growth of the nanocrystalline ZnSe.

A Solvothermal Elemental Reaction To Produce Nanocrystalline ZnSe

Elemental direct combination to synthesize ZnSe and CdSe only occurs at very high temperature. However, in this paper, a simplest hydrothermal elemental-direct-reaction method to produce nanocrystalline ZnSe and CdSe is established, only using water as reaction medium. It greatly decreases the temperature for the direct reaction of Zn, Cd with Se and will be helpful to the synthesis of other nanocrystalline semiconductors.

Low-temperature elemental-direct-reaction route to II-VI semiconductor nanocrystalline ZnSe and CdSe.

Template free-solvothermaly synthesized copper selenide (CuSe, Cu2-xSe, β-Cu2Se and Cu2Se) hexagonal nanoplates from different precursors at low temperature

We successfully realized ZnCdSe quantum dots on a cleavage-induced ZnSe (110) surface by depositing a ZnSe/ZnCdSe/ZnSe heterostructure under growth conditions that cannot lead to layer-by-layer growth of ZnSe. This growth mode introduces surface roughness to the newly deposited ZnSe layer, and ZnCdSe quantum dots are then formed. Cathodoluminescence and microphotoluminescence measurements demonstrate the formation of quantum dots.

E. Edamatsu

Papers

Naturally formed ZnCdSe quantum dots on ZnSe (110) surfaces