摘要
采用射频磁控溅射在石英衬底上制备了c轴择优取向的ZnO薄膜,利用蚀刻技术制备了MSM结构的光导型紫外探测器。在3V偏压下,器件的暗电流小于250nA,光响应峰值在370nm,响应度是0.34A/W。其紫外(360nm)与可见光(420nm)的抑制比为4个数量级。器件的光响应时间上沿仅为20ns。
In recent years, ultraviolet （UV） photodetector has drawn a great deal of interest, due to their potential application such as solar astronomy, fire alarm and combustion monitoring, missile plume detection, space-to-space transmission. Zinc oxide （ZnO） has large exciton binding energy （60 meV） at room temperature, and a large band gap at room temperature （3.37 eV）, and low power threshold for optical pumping at room temperature, high electromechanical coupling factor and high stability under hard conditions, ZnO is recognized as promising material in the uhraviolet （UV） detectors. High quality ZnO films can be obtained by various deposition techniques such as radio frequency （rf） magnetron sputtering technique, pulsed laser deposition （PLD） , metalorganic chemical vapor deposition （ MOCVD）, and also molecular beam epitaxy （MBE）. Among these techniques,the operation of radio frequency magnetron sputtering technique is simply and lower cost.
ZnO thin rims were grown on quartz substrates using radio frequency （rf） magnetron sputtering technique. Before sputtering, the quartz substrates were cleaned in an ultrasonic bath with acetone, ethanol and de-ionized water at room temperature and the zinc（99. 999% ） target was etched with diluted nitric acid to remove the contamination. The base pressure of sputtering chamber was evacuated to be below 5 × 10^-4 Pa, and then filled to 1.0 Pa with mixed gases of 99.99% pure Ar and O2 ,which were introduced into the sputtering chamber though a set of mass flow controllers with the rates of 60 and 20 sccm （ standard cubic centimeter perminute）, respectively. The target-substrate distance was maintained at 50 mm and the substrate temperature was controlled at 400 ℃. The rate of deposition was adjusted so as to have a film thickness of nearly 400 nm during the film growth. The MSM structure with interdigitated configuration on the ZnO thin films was obtained by lithography and wet etching. It consists of 12 fingers at each electrode 5 μm wide and 500 μm long and have an interelectrode spacing of 5 μm. The 0-20 XRD patterns of the ZnO films indicated that the highly caxis oriented film was grown. The PL spectrum of the ZnO thin film taken at room temperature shows a luminescence peak at 3.3 eV. With the applied bias below 3 V, the dark current of the ZnO MSM UV detector is below 250 nA. The typical responsivity peaked at around 370 nm, and had values of 0.34 A/W. In addition, the UV （360 nm） to visible （420 nm） rejection ratio of around four orders can be extracted from the spectra response. Furthermore, the transient response measurement revealed its fast photoresponse with a rise time of 20ns.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2008年第6期1027-1030,共4页
Chinese Journal of Luminescence
基金
国家重点基金(50532050)
国家“973”计划(2008CB307105,2006CB604906)
国家自然科学基金(60676059,60506014)
教育部新世纪优秀人才支持计划(NCET-07-0122)资助项目
关键词
ZNO薄膜
MSM
光导紫外探测器
射频磁控溅射
ZnO thin films
MSM
photoconductive UV detector
radio frequency magnetron sputtering
