Visible–blind photoresponse of GaN-based surface acoustic wave oscillator

Abstract

We describe the photoresponse of GaN-based surface acoustic wave (SAW) delay-line oscillator operating in the 200 MHz range. The decrease in oscillator frequency under ultraviolet illumination of GaN transducer is caused by the SAW velocity decrease due to the acoustoelectronic interaction with photoconductivity electrons. The oscillator frequency shift reaches its maximum value at 365 nm and drops to zero above 400 nm with visible/ultraviolet rejection ratio more than 100. The optical quenching of the photoconductivity in GaN was observed. These results demonstrate the potential of the GaN-based SAW oscillators for applications as visible–blind remote UV sensors.

ZnO based surface acoustic wave ultraviolet photo sensor

“…It exhibits excellent piezoelectric, optical, and semiconducting properties, and finds application in transparent conductor, thin film gas sensor, varistor, surface acoustic wave (SAW) devices, optical wave-guides, acoustooptic modulators/deflectors, ultraviolet (UV) LASER source, and UV detectors [1][2][3][4][5][6][7][8][9][10]. Its easy processing and tunable properties make ZnO as one of the highly researched materials in these days [10][11][12].…”

“…The response of SAW devices is very sensitive to any external perturbation that is taking place on its surface. This behavior of SAW device can be utilized for various applications like gas sensors, chemical sensors, biological sensors, optical sensors etc., if the medium between the input and output interdigital transducers (IDTs) is covered by a sensing layer [3][4][5][6][7][8][9]. Probably the most interesting application of surface acoustic waves is a phenomenon known as acoustic charge transport (ACT).…”

Brillouin scattering determination of the surface acoustic wave velocity in InxGa1−xN: A probe into the elastic constants

“…2,3 On the other hand, GaN-based SAW delay-line oscillators have shown their potential as visible-blind remote UV sensors. 4 Given that the bandgap of In x Ga 1-x N can be tuned from 0.64 eV (x ¼ 1) to 3.4 eV (x ¼ 0) 5 and that the alloy exhibits a higher electromechanical coupling than GaN, InGaN-based SAW devices are good candidates for sensitive visible light sensors.…”

Investigation of a GaN-Based SAW Oscillator with respect to UV Illumination and Temperature

“…Frequency response of a GaN-based SAW delay-line oscillator to ultraviolet (UV) illumination has been demonstrated for the rst time in [1,2]. The eect has been found to be selective with respect to the wavelength of the incident light it nearly vanishes when the wavelength exceeds 400 nm [2].…”

“…The eect has been found to be selective with respect to the wavelength of the incident light it nearly vanishes when the wavelength exceeds 400 nm [2]. Later on, investigation of SAW interaction with UV light was extended to other types of materials: ZnO [3], AlN [4], AlGaN [5].…”