Semiconducting In2S3 quantum dots in thin film form: sonochemical versus conventional chemical synthesis and investigation of their structural and optical properties

Abstract

Indium(III) sulfide quantum dots were deposited in thin film form using both a conventional chemical bath deposition method and a sonochemical route. The developed routes allow deposition of cubic α-In2S3 nanocrystals in thin film form. The as-deposited films produced by the conventional and sonochemical approaches are highly nanocrystalline, with average crystal sizes of 2.5 and 2.0 nm correspondingly (as determined from the Scherrer formula), which increase to 4.1 nm upon annealing treatment, due to coalescence and crystal-growth processes. Refinement of the lattice-constant value in the case of asdeposited and annealed films was performed using linear regression analysis. Blue-shifted band-gap energy values of as-deposited films with respect to those corresponding to bulk specimen, accompanied with the red shift of absorption onset upon annealing, strongly indicate the quantum-dot behavior of the synthesized nanocrystals. The detected threedimensional quantum-confinement effects in the synthesized nanocrystals were discussed in terms of the Brus model. On the basis of optical spectroscopic data, we estimated the Bohr's excitonic radius value in this semiconductor.

Sonochemically Synthesized 3D Assemblies of Close-Packed In2S3Quantum Dots: Structure, Size Dependent Optical and Electrical Properties

“…The described treatment of the substrates eventually leads to formation of small Sn(IV) oxide crystals randomly distributed on their surfaces, serving as nucleation centers which actually initiate heterogeneous nucleation processes and subsequently enable strong adhesion of the QD solids onto the substrate surface. 38 From a chemical point of view, the composition of the reaction system was carefully planned, accounting for various thermodynamical and kinetical aspects of chemical deposition of the nanostructured title material in thin film form, 39 although the deposition method was finally optimized by a classical experiment. The sulfide ions were introduced in the reaction system using thioacetamide, while the concentration of indium(III) ions was controlled and kept low throughout the deposition process applying thiosulfate as complexing agent.…”

“…From a chemical point of view, the composition of the reaction system was carefully planned, accounting for various thermodynamical and kinetical aspects of chemical deposition of the nanostructured title material in thin film form, although the deposition method was finally optimized by a classical experiment. The sulfide ions were introduced in the reaction system using thioacetamide, while the concentration of indium(III) ions was controlled and kept low throughout the deposition process applying thiosulfate as complexing agent.…”

Temperature Dependence of the Band-Gap Energy and Sub-Band-Gap Absorption Tails in Strongly Quantized ZnSe Nanocrystals Deposited as Thin Films

“…Continuing our work in the field of low-dimensional semiconductor materials (refs − and references therein), in the present paper, we study the temperature dependence of optical absorption in the case of 3D assemblies of strongly quantized ZnSe QDs, deposited in thin film form by our recently developed chemical deposition method, which is similar to the one presented in ref , but with certain modifications that affected the thin film properties. The range from cryogenic temperatures (11 K) to about 350 K has been covered, putting a special emphasis on the temperature dependence of the band gap and Urbach energy.…”

A Study of Photophysics, Photoelectrical Properties, and Photoconductivity Relaxation Dynamics in the Case of Nanocrystalline Tin(II) Selenide Thin Films

“…Continuing our work on the synthesis and investigation of structural, optical, and photoelectrical properties of low-dimensional metal chalcogenide structures in thin film form, − in the present paper, we focus on a particularly interesting systemtin(II) selenide. This particular material belongs to the group of IV−VI semiconducting compounds.…”

“…A novel chemical route for the synthesis of this semiconductor in thin film form with nanocrystalline character has recently been developed by our group − in the present paper the results from a study of photophysical properties of close-packed SnSe nanocrystals, deposited as continual thin films, are reported. This includes analysis of both static and dynamic phenomena related to the charge-carrier transport properties in thermal equilibrium as well as under the conditions when internal photoelectrical effect is observed in the low-dimensional structures.…”