Browsing by Subject "Ultraviolet detectors"

Now showing 1 - 5 of 5

Open Access
Design, fabrication and characterization of high-performance solarblind AlGaN photodetectors
(SPIE, 2005) Özbay, Ekmel
Design, fabrication, and characterization of high-performance AlxGal-xN-based photodetectors for solar-blind applications are reported. AlxGal-xN heterostructures were designed for Schottky, p-i-n, and metal-semiconductor-metal (MSM) photodiodes. The resulting solar-blind AlGaN detectors exhibited low dark current, high detectivity, and high bandwidth.
Open Access
Dual-color ultraviolet metal-semiconductor-metal AlGaN photodetectors
(AIP Publishing LLC, 2006) Gökkavas, M.; Bütün, S.; Yu, H.; Tut, T.; Bütün, B.; Özbay, Ekmel
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 epitaxial filter layer and the recess etching of the surface. The 11 nm full width at half maximum (FWHM) responsivity peak of the detector that was fabricated on the as-grown surface was 0.12 AW at 310 nm with 10 V bias, whereas the 22 nm FWHM responsivity peak of the detector fabricated on the recess-etched surface was 0.1 AW at 254 nm with 25 V bias. Both detectors exhibited excellent dark current characteristics with less than 10 fA leakage current. © 2006 American Institute of Physics.
Open Access
High bandwidth-efficiency solar-blind AlGaN Schottky photodiodes with low dark current
(Pergamon Press, 2005-01) Tut, T.; Bıyıklı, Necmi; Kimukin, I.; Kartaloglu, T.; Aytur, O.; Unlu, M. S.; Özbay, Ekmel
Al0.38Ga0.62N/GaN heterojunction solar-blind Schottky photodetectors with low dark current, high responsivity, and fast pulse response were demonstrated. A five-step microwave compatible fabrication process was utilized to fabricate the devices. The solarblind detectors displayed extremely low dark current values: 30 μm diameter devices exhibited leakage current below 3fA under reverse bias up to 12V. True solar-blind operation was ensured with a sharp cut-off around 266nm. Peak responsivity of 147mA/W was measured at 256nm under 20V reverse bias. A visible rejection more than 4 orders of magnitude was achieved. The thermally-limited detectivity of the devices was calculated as 1.8 × 1013cm Hz1/2W-1. Temporal pulse response measurements of the solar-blind detectors resulted in fast pulses with high 3-dB bandwidths. The best devices had 53 ps pulse-width and 4.1 GHz bandwidth. A bandwidth-efficiency product of 2.9GHz was achieved with the AlGaN Schottky photodiodes. © 2004 Elsevier Ltd. All rights reserved.
Open Access
High-performance ALGaN-based visible-blind resonant cavity enhanced Schottky photodiodes
(Materials Research Society, 2003-04) Kimukin, İbrahim; Bıyıklı, Necmi; Kartaloğlu, Tolga; Aytür, Orhan; Özbay, Ekmel
We have designed, fabricated and tested resonant cavity enhanced visible-blind AlGaN-based Schottky photodiodes. The bottom mirror of the resonant cavity was formed with a 20 pair AlN/AlGaN Bragg mirror. The devices were fabricated using a microwave compatible fabrication process. Au and indium-tin-oxide (ITO) thin films were used for Schottky contact formation. ITO and Au-Schottky devices exhibited resonant peaks with 0.153 A/W and 0.046 A/W responsivity values at 337 nm and 350 nm respectively. Temporal high-speed measurements at 357 nm resulted in fast pulse responses with pulse widths as short as 77 ps. The fastest UV detector had a 3-dB bandwidth of 780 MHz.
Open Access
ITO-schottky photodiodes for high-performance detection in the UV-IR spectrum
(IEEE, 2004) Bıyıklı, Necmi; Kimukin, I.; Butun, B.; Aytür, O.; Özbay, Ekmel
High-performance vertically illuminated Schottky photodiodes with indium-tin-oxide (ITO) Schottky layers were designed, fabricated, and tested. Ternary and quarternary III-V material systems (AlGaN-GaN, AlGaAs-GaAs, InAlGaAs-InP, and InGaAsP-InP) were utilized for detection in the ultraviolet (UV) (λ < 400 nm), near-IR (λ ∼ 850 nm), and IR (λ ∼ 1550 nm) spectrum. The material properties of thin ITO films were characterized. Using resonant-cavity-enhanced (RCE) detector structures, improved efficiency performance was achieved. Current-voltage, spectral responsivity, and high-speed measurements were carried out on the fabricated ITO-Schottky devices. The device performances obtained with different material systems are compared.