Browsing by Author "Ata, Erhan Polatkan"

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    Fabrication and characterization of high-speed, high quantum efficiency, resonant cavity enhanced Schottky photodiodes
    (1998) Ata, Erhan Polatkan
    Rapidly developing “photonics” technology promises higher bcindwidths of communiccition than any other techniciue did ever. The increasing rate of communication not only alters science and technology, but brings a global cultural exchange, which seems to be one of the most important revolutions in the history. Photodetectors, as vital corniDonents of optoelectronics, cire still being developed to achieve satisfying performances for the increasing communication demcinds. We have designed and fabricated high-speed, high efficiency resonant Ccivity enhanced (RCE) Schottky photodiodes, suitable for 800-850 mil operation wavelengths. We have used two different GaAs/AlGaAs based epitaxial structures to achieve high performance. From one of these structures, we fabricated photodiodes with 50% quantum efficiency and 80 GHz 3-dB bandwidth. The other structure had a design suitable for préfabrication wavelength tuning and adjustable active layer thickness. On this structure, we achieved 20% quantum efficiency along with, world record for RGB photodiodes, over 110 (Hlz 3-dB estimated bandwidth. We investigated effects of active layer, top Au layer, and silicon nitride coating layer thicknesses on the RCE devices. Discrepancy between theory and experiments were also explained briefly. Methods for improving performances of photodiodes has been proposed ¿is possible future work. Possible appliccitions, which may make use of current knowhow on the subject, have also been mentioned.
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    Fabrication, characterization, and extraction of GaAs mesfets
    (1994) Ata, Erhan Polatkan
    Metal Semiconductor Field Effect Transistor (MESFET) is the most widely used active element of today’s microwave industry. After development of the MESFET technology, the microwave industry gained a high acceleration, especially in the telecommunication field. In this study, GaAs MESFETs with various dimesions and geometries were fabricated. Characterization and parameter extraction of these devices were performed, by means of low and high frequency measurements. The low cutoff frequency of the MESFETs produced were attributed to the non-optimized gate recess etch.