Capacitance controlled n-GaN SAW UV sensor

Chivukula, Venkata; Čiplys, D.; Shur, M. S.; Rimeika, R.

doi:10.1109/icsens.2008.4716607

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…For example, the results set forth in Ref. [32] show that the response of the SAW sensor to the UV light focused on the IDTs was up to five times greater than the response obtained by illuminating the propagation path of the wave. This effect is attributed to the decrease in depletion-width at the metal-semiconductor junction under the IDT and it resulted in an increase in the IDTs' capacitance.…”

Section: Discussionmentioning

confidence: 99%

“…Our sensor performances can be optimized in some ways: (1) by choosing the proper ZnO layer thickness and electrical boundary conditions able to ensure higher electroacoustic coefficient K 2 and hence higher sensitivity (according to Equation (3)); (2) by illuminating the IDTs implemented onto the ZnO layer's surface [32]; and (3) by using glass (instead of fused silica) to reduce the production cost, even if at the price of losing the back-surface interrogation.…”

Section: Discussionmentioning

confidence: 99%

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UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica

Caliendo

Benetti

Cannatà

et al. 2023

Sensors

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Zinc oxide (ZnO) thin films have been grown by radio frequency sputtering technique on fused silica substrates. Optical and morphological characteristics of as-grown ZnO samples were measured by various techniques; an X-ray diffraction spectrum showed that the films exhibited hexagonal wurtzite structure and were c-axis-oriented normal to the substrate surface. Scanning electron microscopy images showed the dense columnar structure of the ZnO layers, and light absorption measurements allowed us to estimate the penetration depth of the optical radiation in the 200 to 480 nm wavelength range and the ZnO band-gap. ZnO layers were used as a basic material for surface acoustic wave (SAW) delay lines consisting of two Al interdigitated transducers (IDTs) photolithographically implemented on the surface of the piezoelectric layer. The Rayleigh wave propagation characteristics were tested in darkness and under incident UV light illumination from the top surface of the ZnO layer and from the fused silica/ZnO interface. The sensor response, i.e., the wave velocity shift due to the acoustoelectric interaction between the photogenerated charge carriers and the electric potential associated with the acoustic wave, was measured for different UV power densities. The reversibility and repeatability of the sensor responses were assessed. The time response of the UV sensor showed a rise time and a recovery time of about 10 and 13 s, respectively, and a sensitivity of about 318 and 341 ppm/(mW/cm2) for top and bottom illumination, respectively. The ZnO/fused silica-based SAW UV sensors can be interrogated across the fused silica substrate thanks to its optical transparency in the UV range. The backlighting interrogation can find applications in harsh environments, as it prevents the sensing photoconductive layer from aggressive environmental effects or from any damage caused by cleaning the surface from dust which could deteriorate the sensor’s performance. Moreover, since the SAW sensors, by their operating principle, are suitable for wireless reading via radio signals, the ZnO/fused-silica-based sensors have the potential to be the first choice for UV sensing in harsh environments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica

Caliendo

Benetti

Cannatà

et al. 2023

Sensors

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“…4a) and could not be explained by the acoustoelectric interaction mechanism. They then proposed a novel mechanism based on the photocapacitive effect and demonstrated the influences of UV-induced changes in the IDT capacitance on the phase change of SAW signals [37,38]. Their viewpoint was that the UV-induced phase changes should be attributed to the variations in IDT impedance caused by the photocapacitive effect.…”

Section: Photocapacitive Effectmentioning

confidence: 99%

Surface acoustic wave-based ultraviolet photodetectors: a review

et al. 2020

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“…The photocarriers generated under UV illumination should lead to the increase in the layer conductivity and contribute to the observable change in SAW velocity. However, our earlier investigations have revealed that in addition to the SAW velocity change attributed to the acoustoelectric effect, the interdigital transducers (IDTs), which generate and detect the surface acoustic waves in GaN/sapphire, are influenced by UV light much stronger than the SAW transmission path between the IDTs [10]. Although the response to UV of metalsemiconductor-metal (MSM) electrodes on AlGaN was earlier investigated [11], such devices are usually fabricated on highly conductive films (with doping concentration on the order of 10 17 cm -3 ) and are mostly incapable for supporting SAW waves.…”

Section: Introductionmentioning

confidence: 98%

Surface acoustic wave interdigital transducer response to Deep UV illumination in AlGaN/sapphire

Chivukula

Čiplys

Shur

et al. 2009

2009 IEEE International Ultrasonics Symposium

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Aluminum-gallium nitride (AlGaN) alloys are promising materials for wavelength-tunable solar-blind surface acoustic wave (SAW) ultraviolet (UV) sensors. We investigate the physical origin of SAW frequency/phase change and study the impact of UV illumination on performance of SAW interdigital transducers (IDT) deposited on AlGaN surface. We correlate these investigations with low frequency measurements of IDT photocapacitance and photoconductance. Our results are important for design and development of efficient SAW devices for UV sensing and high performance filters with tunable frequency response for signal processing applications.

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Capacitance controlled n-GaN SAW UV sensor

Cited by 6 publications

References 14 publications

UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica

UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica

Surface acoustic wave-based ultraviolet photodetectors: a review

Surface acoustic wave interdigital transducer response to Deep UV illumination in AlGaN/sapphire

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