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- All Subjects: Silicon
- Creators: Kozicki, Michael N
Description
The field of flexible displays and electronics gained a big momentum within the recent years due to their ruggedness, thinness, and flexibility as well as low cost large area manufacturability. Amorphous silicon has been the dominant material used in the thin film transistor industry which could only utilize it as N type thin film transistors (TFT). Amorphous silicon is an unstable material for low temperature manufacturing process and having only one kind of transistor means high power consumption for circuit operations. This thesis covers the three major researches done on flexible TFTs and flexible electronic circuits. First the characterization of both amorphous silicon TFTs and newly emerging mixed oxide TFTs were performed and the stability of these two materials is compared. During the research, both TFTs were stress tested under various biasing conditions and the threshold voltage was extracted to observe the shift in the threshold which shows the degradation of the material. Secondly, the design of the first flexible CMOS TFTs and CMOS gates were covered. The circuits were built using both inorganic and organic components (for nMOS and pMOS transistors respectively) and functionality tests were performed on basic gates like inverter, NAND and NOR gates and the working results are documented. Thirdly, a novel large area sensor structure is demonstrated under the Electronic Textile project section. This project is based on the concept that all the flexible electronics are flexible in only one direction and can not be used for conforming irregular shaped objects or create an electronic cloth for various applications like display or sensing. A laser detector sensor array is designed for proof of concept and is laid in strips that can be cut after manufacturing and weaved to each other to create a real flexible electronic textile. The circuit designed uses a unique architecture that pushes the data in a single line and reads the data from the same line and compares the signal to the original state to determine a sensor excitation. This architecture enables 2 dimensional addressing through an external controller while eliminating the need for 2 dimensional active matrix style electrical connections between the fibers.
ContributorsKaftanoglu, Korhan (Author) / Allee, David R. (Thesis advisor) / Kozicki, Michael N (Committee member) / Holbert, Keith E. (Committee member) / Kaminski, Jann P (Committee member) / Arizona State University (Publisher)
Created2012
Description
This work explores the application and optimization of laser patterning of dielectrics on textured crystalline silicon for improving the performance of industrial silicon solar cells. Current direct laser patterning processes introduce defects to the surface of the solar cell as a result of the film transparency and the intensity variation of the laser induced by the textured surface. As a means of overcoming these challenges, a co-deposited protective masking film was developed that is directly patterned with laser light at greatly depreciated light intensities that allows for selective chemical etching of the underlying dielectric films without incurring substantial defects to the surface of the device. Initial defects produced by the process are carefully evaluated with electron microscopy techniques and their mechanism for generation is identified and compensated. Further, an analysis of the opening fraction within the laser spot is evaluated –the area of removed film within the laser spot divided by the area of the laser spot– and residue produced by the laser process within the contact opening is studied. Once identified, this non-damaging laser process is a promising alternative to the standard screen print and fire process currently used by industry for metallization of silicon solar cells. Smaller contacts may be made with the laser process that are as of yet unattainable with screen printing, allowing for a decrease in shading losses. Additionally, the use of patterning allows for silver-free metallization and improved conductivity in the contacts, thereby decreasing parasitic losses in the device.
ContributorsBailly, Mark (Author) / Bowden, Stuart G (Thesis advisor) / King, Richard R (Committee member) / Kozicki, Michael N (Committee member) / Holman, Zachary C (Committee member) / Arizona State University (Publisher)
Created2018