Novel solar-blind photodetector using AlGaN in combination with a PVDF film

A novel solar-blind detector which combined a AlGaN-based structure and a Poly(vinylidene fluoride)(PVDF) -based pyroelectric detector structure in one chip was fabricated. The pyroelectric response spectra of the PVDF-based pyroelectric structure was measured when the UV light illuminated from the side of the AlGaN-based structure. The peak response voltage was measured as high as 129.6 mV when the light's wavelength was 260 nm and the radiation power was 39.8 nW. The response mechanism was assumed as followed: the light at 260 nm was absorbed by i-Al0.35Ga0.65N layer and the heat energy was generated through the direct recombination of photoexcited-carriers, then the heat transferred to the PVDF layer and a response voltage was got through the pyroelectric effect of the PVDF. To confirm this assumption, another sample which added a porous SiO2 layer between the AlGaN-based structure and the PVDF-based structure was fabricated. Its response spectra showed two peaks, one was at 260 nm and the other was at 300 nm. A large decrease of the peak responsivity at 260 nm was observed, and it's in accordance with the assumed response process as the porous SiO2 layer acted as a heat-isolated layer. At last, the response voltage at different chopping frequency was measured for the device without porous SiO2 layer and had the measured data fitted by utilizing the conventional pyroelectric detector's responsivity equation.