Prof. Albena Ivanisevic Profile

Prof. Albena Ivanisevic

Associate Professor at North Carolina State Univ

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Publications (3)

Proceedings Article | 1 July 2004 Paper

Tissue and cell-based biomimetic templates generated via dip-pen nanolithography

Albena Ivanisevic

Proceedings Volume 5322, (2004) https://doi.org/10.1117/12.530317

KEYWORDS: Natural surfaces, Tissues, Scanning probe lithography, Optical lithography, Humidity, Biomimetics, Atomic force microscopy, Eye, Molecules, Nanolithography

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Proceedings Article | 16 June 2003 Paper

Scanning probe lithography

Dorjderem Nyamjav, Albena Ivanisevic

Proceedings Volume 5037, (2003) https://doi.org/10.1117/12.484991

KEYWORDS: Scanning probe lithography, Polymers, Lithography, Nanolithography, Optical lithography, Magnetism, Particles, Atomic force microscopy, Molecules, Nanoparticles

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Proceedings Article | 17 May 2001 Paper

Integrated LED-photodiode chemical sensor

Jeng-Ya Yeh, Suwandi Rusli, Soraya Pornsuwan, Albena Ivanisevic, Anne-Marie Nickel, Arthur Ellis, Thomas Kuech, Luke Mawst

Proceedings Volume 4285, (2001) https://doi.org/10.1117/12.426898

KEYWORDS: Light emitting diodes, Photodiodes, Electroluminescence, Chemical fiber sensors, Chemical analysis, Semiconductors, PIN photodiodes, Sensors, Measurement devices, Gallium arsenide

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The presence of surface states, which pins the Fermi level within the bandgap, contributes to the degradation in the performance of light-emitting diodes (LEDs) and p-i-n photodiodes due to an increase in the non-radiative recombination rate. Chemical modification on the facet or device surface can greatly enhance the output power of LED's and photocurrent of p-i-n photodiodes. Adsorbing molecules can change either the density or energy distribution of surface states. This effect leads to changes in surface recombination which result in systematic variations in light output, and thus the effect can be used for detection of analytes. This mechanism was used to realize a compact chemical sensor based on III/V LED/Detector structures. Initially, we fabricated InGaAlP/InGaP/InGaAlP double heterostructure (DH) LEDs (400 X 1000 micrometer²) with three different active region thicknesses: 50, 250 and 500 nm. In constant current mode, the DH LED exhibits electroluminescence (EL) at approximately 670 nm for an InGaP active region. The EL intensity changes of the LED in various gaseous ambients (NH₃, NH₂(CH₃), NH(CH₃)₂, N(CH₃)₃, and SO₂) are measured. The data show reproducible trends: DH LED structures with thicker active regions result in larger emission intensity changes due to analyte adsorption. Our findings are consistent with active-layer surface area dependence. Thicker active layer devices have larger carrier losses due to nonradiative surface recombination, and thus show a stronger sensitivity to the surface chemistry. Furthermore, we used this DH LED design to build a highly versatile compact sensor. The MOCVD-grown LED wafer is patterned and chemically etched to fabricate integrated GaAs/AlGaAs edge-emitting LEDs and p-i-n photodiode units. The light emitted from the edge-emitting LEDs is absorbed at the sidewall of the adjacent photodiode, and the resulting photocurrent is measured. The device design concept is based on increasing the ratio of analyte-accessible facet area to the volume of the active region. This integrated LED- photodiode device can serve as an on-line chemical sensor for a variety of analytes.

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