الفهرس 
Printing technology and its applications in optics
Blackbody Radiation TheoryOnly 14 pages are availabe for public view
 |  | from | 157 |  |  |
| | | from | 157 | | |
Abstract
This thesis aims to discuss the fabrication and development of Infrared thermal sources that embed micro-printed carbon nanotubes as an active radiating material. Moreover, the thesis focuses on the study of different printed carbon nanotubes structures including Single-Walled Carbon nanotubes (SWCNTs) and Multi-walled Carbon nanotubes (MWCNTs) based thin films aiming to achieve high emissivity and absorptivity for the source and detector respectively in selected wavelength ranges in near and mid-infrared ranges.
Firstly, a multi-scale modeling technique for CNTs thin films is proposed. The model in its Atomic-level utilizes an extensive Ab-Initio or first-principles Quantum Mechanical (QM) study of the optical properties of different SC-SWCNTs chiralities based on the Density Functional Theory (DFT) using SIESTA DFT code. Afterward, A micro-scale model empowered by the calculated wavefunctions is used to calculate the refractive index of each individual chirality. Then a macro-scale model of homogenous multi-layered CNTs thin films was achieved by utilizing the Transfer Matrix Method (TMM) and the effective refractive index method. The computed results are then compared to spectroscopic measurements.
Optical reflectance and transmission measurements were carried out on both (SC-SWCNTs) and Metallic MWCNTs (M-MWCNTs) showing extremely low values over the desired near-infrared wavelength range. Suggesting high absorption and emission for both materials.
In order to raise the temperature of the CNTs, different micromachined joule heaters are designed and optimized for better thermal distribution within the active area where the CNTs are to be plotted. The thermal simulations were performed on the ANSYS tool with the help of its thermo-electrical model. Then two selected designs (the Rectangular design and the Triple-Ring design)are fabricated using two different fabrication techniques. The former was designed using photolithography for the filament while the latter was fabricated utilizing dry laser etching. However, for both designs, the M-MWCNTs were printed onto the active area using the same printing technique.
Lastly, the two designs were optically characterized using compact FTIR spectrometers. The obtained spectra in the NIR and MIR regions are presented for the two designs and compared. The thesis is divided into six chapters as follows:
Chapter 1:
In this chapter, a brief introduction to the motivation, objectives, and author contributions, in addition to the organization of the thesis are presented.
Chapter 2:
This chapter provides a literature review of micro-printing technology and market, carbon nanotubes basics, carbon nanotubes based device fabrication techniques, as well as the potential of using printable different structures of carbon nanotubes as optoelectronic devices.
Chapter 3:
This chapter presents a multi-scale model for SWCNTs thin films, with an extensive Ab-Initio Quantum mechanical study of the optical characteristics on 51 different SC-SWCNTs chiralities based on DFT using the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA). Then a macro-scale model of homogenous multi-layered CNTs thin films was achieved by utilizing the Transfer Matrix Method (TMM) and effective refractive index.
Chapter 4:
This chapter focuses on designing and optimizing different Platinum joule heaters for raising the CNTs temperature. Followed by the fabrication processes of two selected thermal IR sources, in addition to the printing of M-MWCNTs as active emitting material in such devices.
Chapter 5:
This chapter is dedicated to the optical and thermal measurements of the fabricated IR sources. Firstly, NIR and MIR spectroscopic measurements for the Rectangular-design are presented while applying different bias voltages. Subsequently, the Triple-rings design is characterized in the NIR and MIR and compared to the Rectangular-design results. Followed by thermal images of both designs with and without the plotting of CNTs.
Chapter 6:
This chapter is the concluding chapter that provides a summary of the thesis and the obtained results, in addition to suggesting studies for future work.