Tekin, Baran utku
This thesis reports the development of 12 µm pixel pitch single layer microbolometer structures for use in the 8-12 µm wavelength regions, following recent trends in the last decade in microbolometers. Various pixel structures are designed, simulated, fabricated, and characterized to obtain acceptable detector performance in these small pixels. The pixel structures are improved by reducing the pixel thermal conductance and by using planar type electrode structures where the active material is selected as VWOx (Vanadium-Tungsten Oxide). Predictive modeling with electro-thermal simulations has aided in attaining the best possible pixel structures. Besides that, absorptance is optimized using the cascaded transmission line (CTL) simulation method to improve the pixel absorption between 8-12 µm spectral region show that more than 85% level. Designed detector pixels are fabricated using a CMOS compatible process flow. Each fabrication step is optimized considering a possible array fabrication on CMOS wafers. Then, pixels are characterized electrically, thermally, and optically. These characterizations include temperature coefficient of resistance (TCR), noise, thermal conductance, absorption, responsivity, and thermal time constant measurements. The TCR of the active material, VWOx, is measured around -4 %/K with an optimum resistance value. The thermal conductance values of pixels are measured as low as 20 nW/K. Additionally, the corner frequency is measured 0.85 kHz at 10 μA bias current. Finally, a responsivity value of 37 kV/W at 473 µV is measured for the best-performed fabricated pixel with a low thermal time constant of less than 2 ms, suitable for applications that require high frame rates. Fabrication of 640x480 format FPAs is conducted in the framework of this thesis with the optimized detector structure. Among measured FPAs, the responsivity and operability are measured as high as 10 mV/K and >99%, respectively. Using these measurement results, the lowest NETD value of a 640x480 FPA measured minimum is 200 mK. The success of the developed detector structures is verified through the images obtained from the detectors that are monolithically built on the CMOS readout circuit. It should be noted that this thesis reports the first successfully fabricated 640x480 FPA array using a 12 µm pixel pitch single layer microbolometer in Turkey. The development in this small size FPA production may open a path to different applications to be developed and used in Turkey in the future.


Vibration-based damage identification in beam-like composite laminates by using artificial neural networks
Şahin, Melin (SAGE Publications, 2003-01-01)
This paper investigates the effectiveness of the combination of global (changes in natural frequencies) and local (curvature mode shapes) vibration-based analysis data as input for artificial neural networks (ANNs) for location and severity prediction of damage in fibre-reinforced plastic laminates. A finite element analysis tool has been used to obtain the dynamic characteristics of intact and damaged cantilever composite beams for the first three natural modes. Different damage scenarios have been introdu...
Development of an In-house Computer Code for the Thermal Analysis of Satellites Using Thermal Network Method and Method of Lines
Uygur, Ahmet Bilge; Isik, Hasan Guerguec; Solakoglu, Erhan; Yazicioglu, Almila Guevenc (2009-06-13)
This paper discusses the development of an in-house computer code for the thermal analysis of satellites. The code uses Thermal Network Method (TNM) in conjunction with the Method of Lines (MOL) for the solution of the energy equation in the presence of radiative heat transfer. The predictive accuracy of the code is demonstrated on a test problem involving a cubic satellite with two solar panels and a single representative payload at its center to account for all other possible equipments in the satellite. ...
Uncertainty Analysis of Heat Transfer Predictions Using Statistically Modeled Data From a Cooled 1-1/2 Stage High-Pressure Transonic Turbine
Kahveci, Harika Senem (ASME International, 2014-06-01)
This paper compares predictions from a 3D Reynolds-averaged Navier-Stokes code and a statistical representation of measurements from a cooled 1-1/2 stage high-pressure transonic turbine to quantify predictive process sensitivity. A multivariable regression technique was applied to both the inlet temperature measurements obtained at the inlet rake, the wall temperature, and heat transfer measurements obtained via heat-flux gauges on the blade airfoil surfaces. By using the statistically modeled temperature p...
A Thermal Conductance Optimization and Measurement Approach for Uncooled Microbolometers
Senveli, S. Ufuk; Tanrikulu, M. Yusuf; Akın, Tayfun (2011-04-29)
This paper introduces an optimization approach of thermal conductance for single level uncooled microbolometer detectors. An efficient detector design is required due to the limited availability of silicon area per pixel, i.e., the pixel pitch, and due to the capabilities of the fabrication line. The trade-offs between physical parameters are studied to attain the best performance, including the thermal conductance, the thermal time constant, the effective temperature coefficient of resistance (TCR), and th...
Unified theory of linear instability of anisotropic surfaces and interfaces under capillary, electrostatic, and elastostatic forces: The regrowth of epitaxial amorphous silicon
Ogurtani, Tarik Omer (American Physical Society (APS), 2006-10-01)
The first-order unified linear instability analysis (LISA) of the governing equation for the evolution of surfaces and interfaces under capillary, electromigration (EM), and elastostatic forces is developed. A formal treatment of the thermomigration (Soret effect) driven by the nonuniform temperature distribution caused by exothermic phase transformation (growth) at the surface and interfacial layers is presented and its apparent influence on the capillary force in connection with the stability is also esta...
Citation Formats
B. u. Tekin, “DEVELOPMENT OF SMALL SIZE UNCOOLED INFRARED MICROBOLOMETER PIXEL,” M.S. - Master of Science, Middle East Technical University, 2021.