小体积电压输出型ZnO惠斯通电桥式紫外探测单元

A ZnO Wheatstone Bridge Type UV Detection Unit with Small Volume and Voltage Output Capability

针对传统ZnO紫外光探测器无法直接输出电压传感信号而难以与后端信号处理芯片集成的问题,提出并实现了一种小体积电压输出型ZnO惠斯通电桥式紫外探测单元。利用大功率射频磁控溅射SiO_(2)钝化层时高能粒子轰击ZnO薄膜表面的方法增加了ZnO薄膜表面的氧空位缺陷浓度,使ZnO光电导器件桥臂的紫外光响应电流获得近2个数量级的显著提升;在SiO_(2)钝化层上通过射频磁控溅射ZnO作为紫外线遮光层可大大减少ZnO光电导器件桥臂的暗场漏电流。遮光后ZnO光电导器件桥臂的紫外光响应电流显著降低至原先的1/10;所制备的ZnO电桥式紫外探测单元可将入射的紫外光信号直接转换为电压信号输出,且可对1μW~6 mW跨3个数量级强度范围的紫外光进行响应,响应度最高达9 mV/μW,紫外光可见光对比度为143.8,且整个单元体积小于1 mm^(3)。实验结果表明,该ZnO电桥式紫外探测单元具有高响应度、宽响应范围、高紫外光可见光抑制比、可直接输出电压传感信号、体积小等优点,可用于实现具有高集成度的ZnO紫外感算一体芯片。

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 SiO_(2) 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 SiO_(2) 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 1μW 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 mm^(3).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.