Use of multiple acoustic reflections to enhance SAW UV photo-detector sensitivity

Abstract

A new approach to enhance the sensitivity of existing SAW UV-visible photo-detectors based on the monitoring of the multiple reflections of the acoustic waves in the Fourier transform of the frequency response (S21) is demonstrated. By using this concept, it is possible to monitor the UV-visible light in a wide intensity range from very high to ultralow. We present a strategy to obtain an ultrafast SAW UV photo-detector with millisecond response by tuning the deposition conditions of the ZnO film and using the multiple-reflections concept.

Photothermal Effect and Phase Transition in VO2 Enhanced by Plasmonic Particles

“…However, if the initial conductivity of a VO 2 film prepared in some special conditions is smaller than σ M , the attenuation could grow with increased conductivity. More information about similar phenomena may be found in our previous reports on SAW propagating in Zn(Mg, Al)O and ZnO films [ 25 , 26 ].…”

“…A photothermal effect in nanoparticles induced by laser radiation and MIT in VO 2 film is accurately characterized in this manner. Previously, a simplified version of this setup was used by us to monitor the conductivity alteration in ZnO and Zn(Mg,Al)O films under deep UV/UV radiation exposure [ 25 , 26 ].…”

Deep UV light sensitive Zn1−x−y Mg x Al y O films with fast photoelectric response for SAW photodetectors

“…The chamber was evacuated to the base pressure of Sheet conductivity change upon illumination by 15 ns laser pulse at 248 nm. For comparison, that fastest electric photoresponse of pure ZnO film we obtained in previous study upon the excitation by 15 ns pulse at 355 nm showed the fast and slow components kinetics of τ fast =140±80 μs and τ slow =1.3±0.01 ms, correspondingly [12].…”

“…Moreover, the highly photosensitive ZnO layers normally however show inadmissibly slow photoresponse and long recovery times of 2.4-30 s and only in rare studies faster responses were achieved [7][8][9][10][11]. By exploiting the approach of multiple SAW reflections one may obtain detectors with simultaneously fast photoresponse and high sensitivity to UV light [12].…”

“…And vice-versa a SAW is too much attenuated when the film is too much doped by Al and initial conductivity is high. The compromise can be found when multiple SAW reflections are used for UV detection [12]. Alternatively, as we shown in further discussion, by moderate Al doping at ∼1 at% and by changing the film growth temperature one may tune the initial sheet conductivity of Zn(Mg, Al)O film in broad range passing through the maximum of SAW attenuation and also two more important ranges where attenuation altersnonlinear under illumination by UV light.…”