Date of Final Oral Examination (Defense)
Type of Culminating Activity
Master of Science in Electrical and Computer Engineering
Electrical and Computer Engineering
Maria I. Mitkova, Ph.D.
Harish Subbaraman, Ph.D.
David Estrada, Ph.D.
Though Additive manufacturing technology has been developing for 30 years, in recent years, it gets researchers’ and industries’ attention for new expansion in fabricated electronics devices, especially on a flexible substrate. This technology allows fabricating complex design of electronics devices with multi-functionality. Its application has been significantly expanded to different fields such as sensors and other device prototypes for nuclear facilities, aerospace manufacturing, bio-medical, solar energy, etc. due to its low-cost efficiency and sustainable manufacturing. It has a huge advantage over traditional methods such as lower materials waste during production, avoiding complex etching system and harmful chemicals, simplified assembly system eliminating lithography, etching, and packaging process.
This work is focused on developing a fabrication process of GexSe100-x (x=20, 30, 40) based Chalcogenide glass (ChG) printed space-grade radiation sensing device for NASA space exploration application using additive manufacturing technology. By following this fabrication process, astronauts can fabricate a radiation sensor in the international space station to reduce high transport cost and payload. The function of this radiation sensing device depends on triggered by irradiation Ag+ ions migration into a Ge-Se based ChG printed films, as a result of which conductivity increases several orders of magnitude. These studied devices were printed on different substrates, including lightweight flexible substrates at room temperature.
The research work presented in this thesis is divided into four major parts; these are: (i) Ge-Se based ChG ink formation, (ii) printing of the ChG ink on the substrate and sintering process, (iii) printed films analysis, and (iv) device fabrication & testing. Although two types of inks were produced, such as dissolution based ChG inks and nanoparticles based ChG inks, this work mainly focuses on the dissolution based ChG inks fabricated devices, because of the complexity of ink formation and the important correlated effects of the interaction of the ChG and solvents.
The inks were characterized by different methods such as tensiometer measurement of the contact angle of ink with the substrate, the dynamic light scattering (DLS) to check the particles’ size, and viscometer to measure the viscosity of inks. The inks can be modified for use in different types of printers by varying their viscosity, particle size, and solvents. Different kinds of printing methods were used for printing on the substrates with ChG inks, such as screen printing and inkjet printing. The printer’s parameters were optimized for obtaining a good printing pattern. The sintering process also was optimized to evaporate solvents and create a solid film. The effects of different UV light radiation doses and Xe+ irradiation on the ChG printed film devices were studied and analyzed in order to give proof of concept of the printed radiation sensor operation. Different kinds of materials and structural characterization methods such as energy dispersive x-ray spectroscopy (EDS), scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction spectroscopy (XRD) and Raman spectroscopy have been used to study and analyze the printed ChG compositions, and verify the occurrence of oxidation, topography, surface roughness and structural changes at different radiation doses. These studies help to understand the origin of printed materials characteristics, which is a vital part of establishing a bridge between materials’ parameters and device performance. The last part of this work is fabrication of the radiation sensing devices and their testing under different irradiation doses. The ChG printed radiation sensing devices based on all studied compositions and applied solvents were tested using a semiconductor parameter analyzer and probe station. The conductivity change results were presented as a function of radiation doses. The radiation-induced Ag diffusion process was studied to identify the perfect working device. The Ag diffusion was investigated by EDS and XRD spectroscopy to determine the Ag diffusion by-products forming, their crystal sizes, and compositional changes of the hosting ChG after Ag diffusion. Reversible dissolution based screen printed devices were also fabricated and tested using the same conditions. Along with that, these devices have also been tested under different energy of Xe+ ions irradiation. All the results of dissolution based inks and devices, including ink characterizations, printed film analysis, and device performance were compared with the nanoparticles based inks and devices. The performance of devices strongly depends on the composition of ChG.
Ullah, Shah Mohammad Rahmot, "Studies on Space Grade Nano-Iconic Radiation Sensors Using Additive Manufacturing Technology" (2020). Boise State University Theses and Dissertations. 1727.