Investigation of Structural and Optical Properties of Nanocrystalline ZnO

The structural quality of material (concentration and nature of defects) and optical properties (intensity and spectral emission range) of semiconductor materials are usually closely correlated. The idea of this work was to carry out a basic characterization of the structural (by X-ray diffraction technique and scanning electron microscopy) and optical (by micro photoluminescence measurements) properties of nanocrystalline ZnO samples and find a correlation. A number of ZnO samples prepared by atmospheric pressure metalorganic chemical vapor deposition at different regimes and on different substrates were investigated. According to the aim of the work the most important results can be summarized as following. The analysis of ZnO nanocrystalline structures deposited on Si (100) substrates have displayed a dependence of structural quality, morphology and microstructure as well as the optical spectral purity on the deposition temperature. The deposition at 500 ºС resulted in the massive of 1D ZnO nanopillars that demonstrated the best optical properties: a mono-emission in the ultraviolet spectral range was observed. Moreover, the results of microstructure investigation give a suggestion to the explanation of the ZnO nanopillars growth. The results obtained from ZnO on sapphire substrates revealed a moderate influence of the oxygen content during deposition on the structural quality of zinc oxide…


1. Introduction
1.1 Brief overview of ZnO characteristics
1.2 Comparison of different semiconductors
1.3 Motivation and aim of the work
2. Fundamental properties of ZnO
2.1 Crystal structure
2.2 Lattice parameters
2.3 Electronic band structure
2.3.1 Band gap engineering
2.4 Properties of wurtzite ZnO
2.4.1 Optical Properties
2.4.2 Thermal Properties
2.4.3 Electrical Properties
2.5 Doping and defects in ZnO
3. Characterization techniques
3.1 X-ray Powder Diffraction
3.1.1 Generation of X-ray
3.1.2 Bragg’s Law
3.1.3 Crystallite size measurement
3.1.4 Determination of lattice parameters
3.2 Scanning Electron Microscopy
3.2.1 SEM setup
3.3 Photoluminescence
3.3.1 Radiative recombination mechanisms observed in PL
3.3.2 Micro-photoluminescence spectroscopy
3.3.3 Experimental setup
4. Properties of foreigen substrate
4.1 Substrate effects
4.1.1 Sapphire (α-Al2O3)
4.1.2 Silicon (Si)
4.1.3 Silicon carbide (SiC)
5. Growth of ZnO
5.1 Growth techniques
5.2 Cleaning of substrates
5.3 Growth of ZnO by APMOCVD
6. Results and discussion
6.1 Formulas used for calculations
6.2 Properties of ZnO grown on Si (100) at different substrate temperatures
6.3 Properties of ZnO grown on sapphire (0001) substrate
6.4 Properties of ZnO grown on ZnO/ZnO:Ga/Al2O3 (0001)
6.5 Properties of ZnO grown on SiC substrate
6.6 Summary
7. Future work

Author: Hussain, Sajjad

Source: Linköping University

Download URL 2: Visit Now

Leave a Comment