小体积电压输出型ZnO惠斯通电桥式紫外探测单元

Aiming at the problem that traditional ZnO UV photodetectors are difficult to integrate with signal processing chips because photodetectors cannot output a voltage sensing signal directly, a ZnO Wheatstone bridge type UV detection unit with small volume and voltage output capability is proposed and realized. The concentration of oxygen vacancy defects on the surface of ZnO thin film can be dramatically increased through the high-energy ions impact during the high-power RF magnetron sputtering of SiO₂ passivation layer. As a result, the UV photoresponse current of the ZnO photoconductive device bridge arm is enhanced by about two orders of magnitude. Utilizing the RF magnetron sputtered ZnO on the SiO₂ passivation layer as the UV light shielding layer, the dark leakage current of the ZnO photoconductive device bridge arm can be significantly decreased. After depositing ZnO UV light-shielding layer, the ZnO photoconductive device bridge arm's UV photoresponse current dramatically decreases to one tenth of that before deposition. The as-fabricated ZnO Wheatstone bridge type UV detection unit can directly convert input UV light signal to voltage signal output, with a broad UV light power sensing range of over three orders of magnitude from 1 μW to 6 mW. The maximum responsivity of the detection unit can reach 9 mV/μW, with a UV-Vis block ratio as high as 143.8. Besides, the total volume of the detection unit is smaller than 1 mm³. These results indicate that, the proposed ZnO Wheatstone bridge type UV detection unit has the advantages of high responsivity, broad UV light power sensing range, high UV-Vis block ratio, voltage output capability and small volume, and has great potential to realize highly integrated ZnO UV sensing-calculating integrated circuit chip.