Surface properties of CdS nanoparticles

Abstract

With a view to contribute to the understanding the surface effects on optical properties process, and its hole in the electronic properties of the nanoparticles, CdS based nanoparticles are characterised by different experimental techniques and the experimental results compared to density functional theory calculations. Our results indicate that cubic CdS nanoparticles present a strong structural deformation, hexagonal reconstructed structures preserve their lattice behaviour. Both cubic and hexagonal CdS nanoparticles are S-terminated after relaxation, even when mildly Cd-rich nanoparticles are considered. A broad peak observed in our PL measurements is interpreted as an experimental evidence of the surface related peak observed around 1.8 eV in our calculated DOS for the hexagonal relaxed structure.

Photoluminescence of CdS nanoparticles embedded in a starch matrix

“…Recently, the hydroxyl groups of starch have also been employed to stabilize metallic particles of Ag and Ag 2 S [33]. In our case, the cadmium-rich semiconductor nanoparticles form a stable complex with starch, though this type of particles is always S-terminated [27]. Consequently, the scheme proposed by Rutot-Houzé [34], displayed in Fig.…”

“…4 reveal extra features when the analysis is performed as a function of the measurement temperature. In quantum dots (QD), owing to the high surface-to-volume ratio, the impurity levels into the forbidden band gap are localized at the surface of the particle [26,27]. In order to explain the forbidden interband electronic transitions in CdS-QD, impurity levels have been proposed in a number of works, and in some cases these impurity levels have been associated to the ligand material at the surface of the particle [23,[28][29][30].…”

Effect of the composition of the reaction mixture on the preparation of L-cysteine-stabilized CdS nanoparticles and their optical properties

“…A similar problem has been discussed by Vorokh [14] and Faver [15], who discovered by computer analysis that small CdS NP (AE < 5 nm) have disordered structure differing from the crystal structure of wurtzite and sphalerite characteristic for bulk crystals of this semiconductor. Furthermore, we may propose that the difference in dimensions and, probably, the mechanism for growth of the CdS NP in the case of excess of different ions is related specifically to the difference in the structure of the core of the nanoparticles in the initial stages of growth.…”

“…Coefficients k 1 …k 15 were determined using the experimental data according to Gorman [11] and Novik [12]. The starting region of compositions of the three components used most often for the preparation of CdS/L-Cys is shown in Fig.…”

Optical Processes in Nanostructured Semiconductors

“…Theoretical photoluminescence spectrum corresponding to the spectrum of CdS nanoparticles obtained in Ref. [7] are shown in Figure 5. Nanoparticles were synthesized in water solution of (NH 4 2 S and Cd(NO 3 2 .…”