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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