结合AlGaN和PVDF的新型日盲紫外探测器的研究

制作了一种新型的结合了AlGaN材料结构和Poly（vinylidene fluoride）（PVDF）热释电材料的日盲紫外探测器。当紫外光从AlGaN一侧背照射至器件上时，测量PVDF两端的热释电响应光谱，测得峰值响应在入射光波长为260 nm处，响应电压高达129.6 mV（此时辐射功率为39.8 nW）。器件响应机理为:紫外光被i-Al0.35Ga0.65层吸收，产生光生载流子并复合生热，热量通过AlGaN材料传导给PVDF结构的电极，温度升高，PVDF对温度变化产生响应。为了进一步验证，制作了对比器件，即在AlGaN结构和PVDF结构之间加了一层多孔SiO2隔热层，测得的响应光谱中有两个峰值，一个在260 nm，另外一个在300 nm。与参考器件相比，在260 nm处的响应电压大大减小，说明了利用热效应探测的可行性。另外，测量了不同频率下的器件响应并对其进行理论拟合，深入研究300 nm处的响应机理。

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.