Vapor-phase synthesis and characterization of ZnSe nanoparticles

Compound semiconductor nanoparticles are an exciting class of materials whose unique optical and electronic properties can be exploited in a variety of applications, including optoelectronics, photovoltaics, and biophotonics. The most common route for synthesizing such nanoparticles has been via liquid-phase chemistry in reserve micelles. This paper discusses a flexible vapor-phase technique for synthesis of crystalline compound semiconductor nanoparticles using gas-phase condensation reactions near the stagnation point of a counterflow jet reactor. ZnSe nanoparticles were formed by reacting vapors of dimethylzinc: triethylamine adduct and hydrogen selenide at 120Torr and room temperature (28°C). No attempt was made to passivate the surface of the particles, which were collected as random aggregates on silicon wafers or TEM grids placed downstream of the reaction zone. Particle characterization using TEM, electron diffraction, Raman and EDAX revealed that the aggregates consisted of polycrystalline ZnSe nanoparticles, almost monodisperse in size (with diameters of ∼40nm). The polycrystalline nanoparticles appear to have been formed by coagulation of smaller single-crystalline nanoparticles with characteristic size of 3-5 nm.