基于4H-SiC肖特基势垒二极管的γ射线探测器  

γ-ray detector based on n-type 4H-SiC Schottky barrier diode

作　　者：杜园园[1] 张春雷[1] 曹学蕾[1] 

机构地区：[1]中国科学院高能物理研究所,粒子天体物理重点实验室,北京100049

出　　处：《物理学报》2016年第20期212-219,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11203026)资助的课题~~

摘　　要：针对极端环境下耐高温和耐辐照半导体核探测器的研制需求,采用外延层厚度为100μm的4H碳化硅(4H-SiC)制备成肖特基二极管探测器,研究了该探测器对^(241)Am源γ射线的能谱响应.采用磁控溅射金属Ni制备了肖特基二极管的欧姆接触和肖特基接触,利用室温电流-电压和电容-电压测试研究了二极管的电学特性.欧姆特性测试表明,1050°C退火时,欧姆接触特性最好.从正向电流-电压曲线得出二极管肖特基势垒高度为1.617 eV,理想因子为1.127,表明探测器具备良好的热电子发射特性.从电容-电压曲线获得二极管外延层净掺杂浓度为2.903×10^(14)cm^(-3),并研究了自由载流子浓度在外延层中的纵向分布.在反向偏压为500 V时,二极管的漏电流只有2.11 nA,具有较高的击穿电压.测得在-300 V条件下,SiC二极管探测器对能量为59.5 keV的γ射线的能量分辨率为9.49%(5.65 keV).Silicon carbide（SiC） is a wide band-gap, high-temperature-resistant, and radiation-resistant semiconducting material, which can be used as a radiation detector material in harsh environments such as high radiation background and high temperatures. Schottky barrier diode radiation detectors are fabricated using 100 μm-thick n-type 4H-SiC epitaxial layers for low energy γ-ray detection. The spectrum responses of 4H-SiC Schottky barrier detectors are investigated by irradiation of γ-ray from ^241Am source. Schottky diodes are prepared by magnetron-sputtering 100 nm-thick nickel on epitaxial surface（Si face） to obtain Schottky contact and Ni/Au on substrate surface（C face） to obtain Ohmic back contact, respectively. Room temperature current-voltage（I-V） and capacitance-voltage（C-V） curves are measured to study the properties of Schottky diodes. Ohmic characteristic measurement shows that the Ohmic contact is formed after annealing in a temperature range of 900–1050℃, and the lowest specific contact resistivity of 2.55 × 10^-5Ω·cm^2 is obtained after annealing at 1050℃. The forward I-V curve reveals that the Schottky barrier height and the ideality factor are 1.617 e V and 1.127, respectively, indicating that the main current transportation process is the thermal electron emission. From the C-V curve, besides the net dopant concentration being inferred to be 2.903 × 10^14 cm^-3,the profile of the free carrier concentration in epitaxial layer is also studied. A comparision of the reverse I-V curves of Si C Schottky diodes with different epitaxial layer thickness shows that the diode with 100 μm-thick epitaxial layer has a constant reverse leakage current when the bias voltage is less than 400 V, showing good rectification characteristics.By applying a reverse bias of 500 V, the diode has a leakage current of 2.11 nA, exhibiting a relatively high breakdown voltage. The depletion layer width of Si C detector is calculated to be 94.4 μm at 500 V, indicating that the epitaxial layer is al

关 键 词：4H-SIC 宽禁带半导体 肖特基二极管 Γ射线探测器 

分 类 号：TL816.2[核科学技术—核技术及应用]