cds & cdse nanocrystals grown in glass nazanin hosseinkhah 1382/3/12
DESCRIPTION
Three Stages of Nanocrystals: Decomposition Nucleation Growth at The Expense of Solved Matter Recondensation GrowthTRANSCRIPT
CdS & CdSe Nanocrystals Grown in
Glass
Nazanin Hosseinkhah
1382/3/12
In Atomic Scale: Electronic Properties Optical Properties Magnetic Properties Thermodynamic Properties
Due to the quantum confinement of free carries
Three Stages of Nanocrystals:
Decomposition Nucleation
Growth at The Expense of Solved Matter
Recondensation Growth
Techniques to Grow Semiconductor NC: Co-Sputtering Technique
Ion Implantation
Wet Chemistry
The Melting
Radio-Frequency Magnetron Sputtering Advantages:
1 Inexpensive2 Suitable Way for Growing Nanoparticles
Mean Diameter of NC 4-6 nm
High Resolution Transmission Electron Microscopy (HRTEM)
Low Concentration Homogeneous Distribution High Concentration Columnar Structure
Low Con. 4.9nmHigh Con. 5.8nm
Low Con. 4.9nmHigh Con. 5.8nm
NO Sign of Quantized Energy Level !
Ion ImplantationAdvantages:1 More Freedom From thermodynamical limitation2 Extreme Chemical Purity3 Compatibility With Planar Technology
Disadvantage:1 Damage The Lattice by Implantation
Depth Implantation & Annealing Parameters
Application Tunable Light Absorbers
X-Ray Result Hexagonal,Wurtzite Structure
Ion Dose Control The StoichiometryEnergy Depth 10nm Particles
Different Ion Doses:
T = Constant.
D1 = 2.5 * 10^16 D2 = 5 * 10^16 D3 = 1 * 10^17
D3>D2>D1
Derivation of Absorbance:
Theoretical Background
Solid-Phase (Glass) High Activation Energy for Nucleation & Diffusion Formation Limited by Homogeneous Nucleation (Thermodynamic Concentration Fluctuation of The Reactants)
Delta Gv Is Bulk Free Energy Per Unit Volume Is Phase Interaction Energy Per Unit Area
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