05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access High‐performance MEMS shutter display with metal‐oxide thin‐film transistors and optimized MEMS element(2023) Al Nusayer, Sheikh Abdullah; Schalberger, Patrick; Baur, Holger; Kleber, Florian; Fruehauf, NorbertActive matrix prestressed microelectromechanical shutter displays enable outstanding optical properties as well as robust operating performance. The microelectromechanical systems (MEMS) shutter elements have been optimized for higher light outcoupling efficiency with lower operation voltage and higher pixel density. The MEMS elements have been co-fabricated with self-aligned metal-oxide thin-film transistors (TFTs). Several optimizations were required to integrate MEMS process without hampering the performance of both elements. The optimized display process requires only seven photolithographic masks with ensuring proper compatibility between MEMS shutter and metal-oxide TFT process.Item Open Access Ultraviolet photodetectors and readout based on a‐IGZO semiconductor technology(2023) Schellander, Yannick; Winter, Marius; Schamber, Maurice; Munkes, Fabian; Schalberger, Patrick; Kuebler, Harald; Pfau, Tilman; Fruehauf, NorbertIn this work, real-time ultraviolet photodetectors are realized through metal–semiconductor–metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time tRES, and a good noise equivalent power value NEP.Item Open Access Spatially resolved current- and photodetection based on amorphous indium gallium zinc oxide(2025) Schellander, Yannick; Frühauf, Norbert (Prof. Dr.-Ing.)In the scope of this thesis amorphous indium gallium zinc oxide based thin-film devices and circuits are utilized to create current- and photodetection arrays. These arrays enable the spatial resolution of the charge carrier creation, the electric field distribution and the fluorescence light inside a nitric oxide sensing cell. The experimental setup including the gas cell is part of the quantum nitric oxide sensing experiment, whose goal is to realize a trace gas sensor for the detection of nitric oxide. The sensor principle is based on the thermal ionization of resonant excited electronic states. Thin-film technology can provide an integrated readout of the ionization current. Therefore the development, simulation and characterization of the required current-to-voltage conversion circuits (resistive transimpedance amplifiers) takes up a considerable part of this thesis. Especially the creation of an on-glass unity gain stable operational amplifier design is treated extensively. This includes a theoretical overview on different current-to-voltage converters, operational amplifiers, thin-film devices and technology. A variation of thin-film based photosensing devices is manufactured and characterized. The characterization includes the investigation of the detection efficiency, the sensitivity and the bandwidth. Furthermore the influence of sensor dimensions and operating parameters on the sensor characteristics is determined. Additional the compatibility of photosensors and transistors or readout circuits are elaborated. The functionality of the photosensor arrays is validated by measuring the beam size of an ultraviolet laser at 227 nm. In general the created thin-film devices and circuit have applications in the display field, especially in the subfield of sensor integration into displays. Transimpedance amplifiers can be essential parts in the readout circuits of these sensors. The utilized operational amplifier also has an application in column and row driver circuits of displays.Item Open Access High gain operational amplifier using enhancement and depletion mode a-IGZO TFTs(2022) Schellander, Yannick; Winter, Marius; Ge, Ge; Ouyang, Yunyi; Obermüller, Simon; Schalberger, Patrick; Fruehauf, NorbertAn operational amplifier (OpAmp) consisting of twenty-two dual gate amorphous IGZO (a-IGZO) thin-film transistors (TFTs) is fabricated on a glass substrate. To achieve high voltage gains enhancement and depletion mode transistors are used. The enhancement mode TFTs work as drivers and the depletion mode TFTs act as depletion loads in the OpAmp circuit. The created OpAmp has a voltage gain (G) of 54.80 dB, a cutoff frequency (fc) of 75 Hz, a unity gain frequency (fug) of 10 kHz and a slew rate ts(up/down) of 0.15/0.30 V/µs. Transistors with different threshold voltages Uth on the same substrates are realized by using different semiconductor channel thicknesses. This is possible, as an increasing layer thickness of the semiconductor leads to a reduction of the threshold voltage Uth [1].Item Open Access Printed chip interconnects for microLED displays(2025) Waldner, Kai; Baur, Holger; Schalberger, Patrick; Fruehauf, Norbert; Fuchs, Emmanuel; Ramaswamy, Prasanna; Toomey, Vincent; Drozdek, SławomirThis paper presents a newly developed process for interconnecting microICs with microLEDs through ultra‐precise dispensing of conductive silver‐based paste. Special cleaning and surface energy modification processes have been introduced to achieve interconnects with a width of 5 μm and a minimum pitch of 20 μm. The developed technology is part of the EU funded project “Building Active matrix MicroLED displays By Additive Manufacturing” (BAMBAM), which develops unique manufacturing technologies for realizing microLED displays without TFT backplanes.Item Open Access Large‐area hydrogenated amorphous silicon Schottky photosensor arrays for display integration(2025) Dettling, Marco M.; Schalberger, Patrick; Schellander, Yannick; Fruehauf, NorbertIn this work, a system for the real‐time spatially resolved detection of visible light on a large area is realized on glass. Schottky photodiodes, consisting of hydrogenated amorphous silicon (a‐Si:H) and molybdenum-tantalum (MoTa), are employed as detectors. The detectors exhibit an internal quantum efficiency of up to 70.96% and a response time smaller than 20 μs. The noise equivalent power was measured at 2.424e‐10 W/√Hz. Process compatibility with commonly employed amorphous indium gallium zinc oxide (a‐IGZO) and a‐Si:H thin‐film transistors (TFT) is shown. The driving and real‐time readout of a photosensor array is demonstrated using a microcontroller and a current‐input ADC.