Browsing by Author "Gökkavas, M."
Now showing items 1-20 of 21
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100-GHz resonant cavity enhanced Schottky photodiodes
Onat, B. M.; Gökkavas, M.; Özbay, Ekmel; Ata, E. P.; Towe, E.; Ünlü, M. S. (Institute of Electrical and Electronics Engineers, 1998)Resonant cavity enhanced (RCE) photodiodes are promising candidates for applications in optical communications and interconnects where ultrafast high-efficiency detection is desirable. We have designed and fabricated RCE ... -
45 GHz bandwidth-efficiency resonant cavity enhanced ITO-Schottky photodiodes
Bıyıklı, Necmi; Kimukin, İbrahim; Aytür, Orhan; Özbay, Ekmel; Gökkavas, M.; Ünlü, M. S. (OSA, 2001)We demonstrated high-performance resonant cavity enhanced ITO-Schottky photodiodes. We achieved a peak efficiency of 75% around 820 nm with a 3-dB bandwidth of 60 GHz resulting in a bandwidth-efficiency product of 45 GHz. -
45-GHz bandwidth-efficiency resonant-cavity-enhanced ITO-Schottky photodiodes
Bıyıklı, Necmi; Kimukin, I.; Aytür, O.; Gökkavas, M.; Ünlü, M. S.; Özbay, Ekmel (IEEE, 2001)High-speed Schottky photodiodes suffer from low efficiency mainly due to the thin absorption layers and the semitransparent Schottky-contact metals. We have designed, fabricated and characterized high-speed and high-efficiency ... -
AlGaN-based high-performance metal-semiconductor-metal photodetectors
Gökkavas, M.; Butun, S.; Tur, T.; Bıyıklı, Necmi; Özbay, Ekmel (Elsevier BV, 2007-10)Design, structure growth, fabrication, and characterization of high performance AlGaN-based metal–semiconductor–metal (MSM) photodetectors (PD) are reported. By incorporating AlN nucleation and buffer layers, the leakage ... -
Deep-ultraviolet Al0.75Ga0.25N photodiodes with low cutoff wavelength
Bütün, S.; Tut, T.; Bütün, B.; Gökkavas, M.; Yu, H.; Özbay, Ekmel (AIP Publishing LLC, 2006-03-21)Deep ultraviolet Al0.75Ga0.25N metal-semiconductor-metal photodetectors with high Al concentration have been demonstrated. A metal-organic chemical vapor deposition grown high quality Al0.75Ga0.25N layer was used as a ... -
Design and optimization of high-speed resonant cavity enhanced Schottky photodiodes
Gökkavas, M.; Onat, B. M.; Özbay, Ekmel; Ata, E. P.; Xu, J.; Towe, E.; Ünlü, M. S. (Institute of Electrical and Electronics Engineers, 1999-02)Resonant cavity enhanced (RCE) photodiodes (PD's) are promising candidates for applications in optical communications and interconnects where high-speed high-efficiency photodetection is desirable. In RCE structures, the ... -
Dual-color ultraviolet metal-semiconductor-metal AlGaN photodetectors
Gökkavas, M.; Bütün, S.; Yu, H.; Tut, T.; Bütün, B.; Özbay, Ekmel (AIP Publishing LLC, 2006)Backilluminated ultraviolet metal-semiconductor-metal photodetectors with different spectral responsivity bands were demonstrated on a single Alx Ga1-x N heterostructure. This was accomplished by the incorporation of an ... -
Experimental demonstration of a left-handed metamaterial operating at 100 GHz
Gökkavas, M.; Güven, K.; Bulu, I.; Aydın, K.; Penciu, R. S.; Kafesaki, M.; Soukoulis, C. M.; Özbay, Ekmel (American Physical Society, 2006)The existence of a left-handed (LH) transmission band in a bulk composite metamaterial (CMM) around 100 GHz is demonstrated experimentally. The CMM consists of stacked planar glass layers on which periodic patterns of ... -
Experimental evaluation of impact ionization coefficients in Al xGa1-xN based avalanche photodiodes
Tut, T.; Gökkavas, M.; Bütün, B.; Bütün, S.; Ülker, E.; Özbay, Ekmel (AIP Publishing LLC, 2006)The authors report on the metal-organic chemical vapor deposition growth, fabrication, and characterization of high performance solar-blind avalanche photodetectors and the experimental evaluation of the impact ionization ... -
Fabrication of high-speed resonant cavity enhanced schottky photodiodes
Özbay, Ekmel; Islam, M. S.; Onat, B.; Gökkavas, M.; Aytür, O.; Tuttle, G.; Towe, E.; Henderson, R. H.; Ünlü, M. S. (Institute of Electrical and Electronics Engineers, 1997-05)We report the fabrication and testing of a GaAs-based high-speed resonant cavity enhanced (RCE) Schottky photodiode. The top-illuminated RCE detector is constructed by integrating a Schottky contact, a thin absorption ... -
High bandwidth-efficiency resonant cavity enhanced Schottky photodiodes for 800-850 nm wavelength operation
Ünlü, M. S.; Gökkavas, M.; Onat, B. M.; Ata, E.; Özbay, Ekmel; Mirin, R. P.; Knopp, K. J.; Bertness, K. A.; Christensen, D. H. (A I P Publishing LLC, 1998-05-25)High-speed resonant cavity enhanced Schottky photodiodes operating in 800-850 nm wavelength region are demonstrated. The devices are fabricated in the AlGaAs/GaAs material system. The Schottky contact is a semitransparent ... -
High-speed >90% quantum-efficiency p-i-n photodiodes with a resonance wavelength adjustable in the 795-835 nm range
Özbay, Ekmel; Kimukin, İ.; Bıyıklı, Necmi; Aytür, O.; Gökkavas, M.; Ulu, G.; Ünlü, M. S.; Mirin, R. P.; Bertness, K. A.; Christensen, D. H. (A I P Publishing LLC, 1999-02-22)We report GaAs/AlGaAs-based high-speed, high-efficiency, resonant cavity enhanced p-i-n photodiodes. The devices were fabricated by using a microwave-compatible fabrication process. By using a postprocess recess etch, we ... -
High-speed high-efficiency large-area resonant cavity enhanced p-i-n photodiodes for multimode fiber communications
Gökkavas, M.; Dosunmu, O.; Ünlü, M. S.; Ulu, G.; Mirin, R. P.; Christensen, D. H.; Özbay, Ekmel (IEEE, 2001)In this letter, we report AlGaAs–GaAs p-i-n photodiodes with a 3-dB bandwidth in excess of 10 GHz for devices as large as 60- m diameter. Resonant cavity enhanced photodetection is employed to improve quantum efficiency, ... -
High-speed high-efficiency resonant cavity enhanced photodiodes
Özbay, Ekmel; Kimukin, I.; Bıyıklı, N.; Aytür, O.; Gökkavas, M.; Ulu, G.; Ünlü, M. S.; Mirin, R. P.; Bertness, K. A.; Christensen, D. H.; Towe, E.; Tuttle, G. (Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, United States, 1999)In this paper, we review our research efforts on RCE high-speed high-efficiency p-i-n and Schottky photodiodes. Using a microwave compatible planar fabrication process, we have designed and fabricated GaAs based RCE ... -
High-speed resonant-cavity-enhanced Schottky photodiodes
Ata, Erhan P.; Bıyıklı, Necmi; Demirel, Ekrem; Özbay, Ekmel; Gökkavas, M.; Onat, B.; Ünlü, M. S.; Tuttle, G. (IEEE, 1998)The top-illuminated Schottky photodiodes were fabricated by a microwave-compatible monolithic microfabrication process. Fabrication started with formation of ohmic contacts to n+ layers. Mesa isolation was followed by a ... -
High-speed widely-tunable >90% quantum-efficiency resonant cavity enhanced p-i-n photodiodes
Bıyıklı, Necmi; Kimukin, İbrahim; Aytür, Orhan; Gökkavas, M.; Ulu, G.; Mirin, R.; Christensen, D. H.; Ünlü, M. S.; Özbay, Ekmel (IEEE, 1998)Widely-tunable high-speed resonant cavity enhanced p-i-n photodiodes were designed, fabricated and tested for operation around 820 nm. The structure was grown by solid-source MBE on GaAs substrates and features high-reflectivity ... -
Improved selectivity from a wavelength addressable device for wireless stimulation of neural tissue
Seymour, E. Ç.; Freedman, D. S.; Gökkavas, M.; Özbay, Ekmel; Sahin, M.; Ünlü, M. S. (Frontiers Research Foundation, 2014)Electrical neural stimulation with micro electrodes is a promising technique for restoring lost functions in the central nervous system as a result of injury or disease. One of the problems related to current neural ... -
Improving the efficiency enhancement of photonic crystal based InGaN solar cell by using a GaN Cap Layer
Gundogdu, T.F.; Gökkavas, M.; Özbay, Ekmel (Hindawi Publishing Corporation, 2014)We studied a high indium content (0.8) InGaN based solar cell design where the active InGaN layer is sandwiched between a GaN cap layer and a GaN spacer layer. The incorporation of the sacrificial cap layer allows for the ... -
Integrated AlGaN quadruple-band ultraviolet photodetectors
Gökkavas, M.; Butun, S.; Caban, P.; Strupinski, W.; Özbay, Ekmel (IOP Publishing, 2012-04-27)Monolithically integrated quadruple back-illuminated ultraviolet metalsemiconductormetal photodetectors with four different spectral responsivity bands were demonstrated on each of two different Al xGa 1-xN heterostructures. ... -
Low dark current metal-semiconductor-metal photodiodes based on semi-insulating GaN
Bütün, S.; Gökkavas, M.; Yu, H.; Özbay, Ekmel (AIP Publishing LLC, 2006)Metal-semiconductor-metal photodetectors on semi-insulating GaN templates were demonstrated and compared with photodetectors fabricated on regular GaN templates. Samples were grown on a metal organic chemical vapor deposition ...