Characterization of vapor-phase-grown ZnSe nanoparticles

Abstract

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.

Influence of substrate temperature on the properties of electron beam evaporated ZnSe films

“…Similar observations were reported earlier by Lu et al [26]. From previous reports, the LO phonon frequency of crystalline ZnSe films was 254 cm -1 and that of single crystal ZnSe was 255 cm -1 at room temperature and for ZnSe polycrystalline nanoparticles, the TO and LO phonon frequencies were observed at 210 and 255 cm -1 respectively, and exhibit a broad Raman peak due to the high surface to volume ratio of small particles [30]. In this work, the LO and TO phonon peaks of the ZnSe films are shifted towards the lower frequency, which may be due to the effect of small size.…”

Preparation and characterization of ZnSe nanocrystals in silica gel-glasses

“…The peak around 257 cm −1 is the first-order longitudinal optical (1LO) phonon Raman spectra of ZnSe NCs doped in silica gelglass. The asymmetric broadening of 1LO phonon peak was related with the size of the ZnSe nanocrystal by the spatial correlation model [10], or phonon confinement effect. A Gaussian localization factor exp(−q 2 L 2 /4) is introduced into the phonon wave function, where L is the correlation length and q is phonon wave vector.…”

Characterization of ZnSe nanocrystals grown by vapor phase epitaxy

“…It is clear that the simplest mechanism that leads to formation of nanocrystals should resemble the process described in Ref. 9. When the hot vapor of ZnSe enters a cooled zone of reactor it becomes supersaturated and undergoes a fast condensation, resulting in singlecrystalline nuclei.…”

“…The growth technique used is a variant of vapor phase epitaxy (VPE) that uses no alien substances except extremely pure hydrogen, which plays the role of a carrier for transfer of the vapor of the source material to the deposition zone. This technique facilitates the growth of really uncontaminated ZnSe as opposed to the previously reported VPE route utilizing reaction between vapors of (CH 3 )Zn:N(C 2 H 5 ) and H 2 Se in a counterflow jet reactor [9]. For many years the ZnSe-based nanostructures have been the focus of much attention for applications in all solid-state blue and green lightemitting devices.…”