Characterization of vapor-phase-grown ZnSe nanoparticles

ZnSe nanoparticles were synthesized by reacting vapors of (CH3)2Zn:N(C2H5)3 and H2Se, diluted in H2, in an opposed flow reactor operating at room temperature and 120 Torr. The particles were collected as random aggregates on silicon substrates and transmission electron microscopy (TEM) grids placed downstream of the reaction zone. Particle characterization using TEM and electron diffraction revealed the presence of polycrystalline nanoparticles with diameter of about 40 nm that were apparently formed from coagulation of smaller nanocrystals with characteristic size of about 4 nm. Raman spectra of the nanoparticles revealed an asymmetrically broadened feature associated with the LO phonon of ZnSe, indicating the presence of smaller single-crystalline grains.