基于高阻ZnO薄膜的光电导型紫外探测器  

Photoconductive UV detector based on high-resistance ZnO thin film

作　　者：祁晓萌 彭文博[1] 赵小龙[1] 贺永宁[1] 

机构地区：[1]西安交通大学电子与信息工程学院,西安710049

出　　处：《物理学报》2015年第19期373-378,共6页Acta Physica Sinica

基　　金：中央高校基本科研业务费专项资金(批准号:xkjc2014011);国家自然科学基金(批准号:60876038)资助的课题~~

摘　　要：本文通过射频磁控溅射法在玻璃衬底上沉积一层ZnO薄膜,制备了Al-ZnO-Al结构光电导型紫外探测器件,并在室温下测试了所制备器件的暗场特性及其对紫外线的响应特性.暗场条件下器件电流特性测试结果表明所制备的ZnO薄膜电阻率达到了3.71×109?·cm,是一种高阻薄膜.在波长365 nm,光强303μW/cm2的紫外线照射下,薄膜的电阻率为7.20×106?·cm,探测器明暗电流比达到了516.40 V偏置电压条件下周期性开关紫外线照时,探测器的上升和下降时间分别为199 ms和217 ms,响应速度快且重复性好,并利用ZnO半导体表面复合慢过程和体复合快过程对瞬态响应过程进行了理论拟合分析.本文研究结果表明,高阻ZnO薄膜紫外探测器具有良好的紫外光电响应特性.As a wide bandgap semiconductor material, ZnO has huge potential in applications such as light emitting devices and sensors. Compared with GaN and SiC, ZnO has a bandgap of 3.37 eV and exciton binding energy of 60 meV at room temperature, indicating it is a promising candidate of UV detector. ZnO based metal-semiconductor-metal photoconductive ultraviolet detector has the advantages of high optical gain and strong responsivity. However, due to the photoconductive relaxation and surface effect of the ZnO material, a ZnO-based photoconductive UV detector has a slow response which is defective for practical application. The intrinsic defects typically generated during the synthesis of ZnO, e.g. oxygen vacancy, should be responsible for the slow response. Therefore, we have fabricated the high-resistive ZnO thin film based UV detector and studied its UV response characteristic. High resistance ZnO thin film is fabricated on glass by RF magnetron sputtering and followed by lift-off photolithography to form Al interdigital electrodes. SEM and XRD images show that the as-fabricated ZnO thin film grows with preferential orientation along c-axis. A linear I-V curve under UV illumination indicates the ohmic contact between Al and ZnO. From these results, we can calculate the resistivities to be 3.71 × 109 Ω·cm and 7.20 × 106 Ω·cm respectively when in the dark and under 365 nm UV light of 303 μW/cm2. The light-to-dark current ratio is up to 516 with bias of 40 V. Besides, the ZnO thin film detector shows a stable, rapid, repeatible and reproducible response with a rise time of 199 ms and a fall time of 217 ms when exposed to periodically switched UV light illumination at a bias voltage of 40 V. Moreover, the detector has a high selectivity for 365 nm UV light and the responsivity is 0.15 mA/W with the intensity of 303 μW/cm2. Furthermore, the transient response process is analyzed using the theory of surface recombination and bulk recombination of ZnO semiconductor. For a high resistance ZnO thin film based UV detec

关 键 词：高阻ZnO薄膜 紫外探测 快速响应 

分 类 号：TN23[电子电信—物理电子学] O484.4[理学—固体物理]