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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100 upm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241Am源射线的能谱响应.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℃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2.9031014 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 upm-thick n-type 4H-SiC epitaxial layers for low energy -ray detection. The spectrum responses of 4H-SiC Schottky barrier detectors are investigated by irradiation of -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 2.5510-5 cm2 is obtained after annealing at 1050℃. The forward I-V curve reveals that the Schottky barrier height and the ideality factor are 1.617 eV 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 2.9031014 cm-3, the profile of the free carrier concentration in epitaxial layer is also studied. A comparision of the reverse I-V curves of SiC Schottky diodes with different epitaxial layer thickness shows that the diode with 100 upm-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 SiC detector is calculated to be 94.4 m at 500 V, indicating that the epitaxial layer is almost fully depleted. The signal of SiC detector through preamplifier displays a relatively low amplitude pulse (15 mV). A typical -ray spectrum response from SiC detector shows 9.49% (5.65 keV) energy resolution for 59.5 keV with a reverse bias of 300 V. The potential causes of poor count rate and energy resolution of fabricated detectors are analyzed in this article. The lower count rate is mainly caused by the narrow depletion layer, resulting in fewer photons deposited in sensitive region which can generate carriers. The poor energy resolution of SiC detector can be attributed to the electronic noise of read-out circuit, the pre-match amplifier circuit for detector needs to be improved, in addition, the extra defects existing in detector caused by increasing thickness of epitaxial layer can also deteriorate the detector performance.
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Keywords:
- 4H-SiC /
- wide-band semiconductor /
- Schottky diode /
- -ray detector
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[17] Shur M, Rumyantsev S, Levinshtein M (translated by Yang Y T, Jia H J, Duan B X) 2012 SiC Mareials and Devices, Volume I&Ⅱ (Beijing:Publishing House of Electroics Industry) pp88-92(in Chinese)[Shur M, Rumyantsev S, Levinshtein M主编(杨银堂, 贾护军, 段宝兴译) 2012碳化硅半导体材料与器件(北京:电子工业出版社)第88–92页]
[18] Zha G Q, Wang T, Xu Y D, Jie W Q 2013 Physics 42 862 (in Chinese)[查钢强, 王涛, 徐亚东, 介万奇2013物理42 862]
[19] Bertuccio G, Casiraghi R 2003 IEEE Trans. Nucl. Sci. 50 175
[20] Lees E J, Bassford J D, Fraser W G, Horsfall B A, Vassilevski V K, Wright G N, Owens A 2007 Nucl. Instrum. Methods Phys. Res. Sect. A 578 226
[21] Jiang Y, Fan X Q, Rong R, Wu J, Bai S, Li L 2012 Nucl. Electron. Detect. Technol. 32 1372 (in Chinese)[蒋勇, 范晓强, 荣茹, 吴建, 柏松, 李理2012核电子学与探测技术32 1372]
[22] Mandal C K, Chaudhuri K S, Nguyen V K, Mannan A M 2014 IEEE Trans. Nucl. Sci. 61 2338
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[1] Rogowski J, Kubiak A 2012 Mater. Sci. Eng. B 177 1318
[2] Siad M, Vargas P C, Nkosi M, Saidi D, Souami N, Daas N, Chami C A 2009 Appl. Surf. Sci. 256 256
[3] Bertuccio G, Caccia S, Puglisi D, Macera D 2011 Nucl. Instrum. Methods Phys. Res. Sect. A 652 193
[4] Nava F, Vittone E, Vanni P, Verzellesi G, Fuochi G P, Lanzieri C, Glaser M 2003 Nucl. Instrum. Methods Phys. Res. Sect. A 505 645
[5] Han C, Zhang Y M, Song Q W, Tang X Y, Zhang Y M, Guo H, Wang Y H 2015 Chin. Phys. B 24 117304
[6] Yuan L, Zhang Y M, Song Q W, Tang X Y, Zhang Y M 2015 Chin. Phys. B 24 068502
[7] Chaudhuri K S, Krishna M R, Zavalla J K, Mandal C K 2013 Nucl. Instrum. Methods Phys. Res. Sect. A 701 214
[8] Mandal C K, Muzykov G P, Chaudhuri K S, Terry R J 2013 IEEE Trans. Nucl. Sci. 60 2888
[9] Flammang W R, Seidel G J, Ruddy H F 2007 Nucl. Instrum. Methods Phys. Res. Sect. A 579 177
[10] Wu J, Lei J R, Jiang Y, Chen Y, Rong R, Fan X Q 2013 High Power Laser Part. Beams 25 1793 (in Chinese)[吴健, 雷家荣, 蒋勇, 陈雨, 荣茹, 范晓强2013强激光与粒子束25 1793]
[11] Wu J, Jiang Y, Gan L, Li M, Zou D H, Rong R, Lu Y, Li J J, Fan X Q, Lei J R 2015 High Power Laser Part. Beams 27 014004 (in Chinese)[吴健, 蒋勇, 甘雷, 李勐, 邹德慧, 荣茹, 鲁艺, 李俊杰, 范晓强, 雷家荣2015强激光与粒子束27 014004]
[12] Jiang Y, Wu J, Wei J J, Fan X Q, Chen Y, Rong R, Zou D H, Li M, Bai S, Chen G, Li L 2013 Atomic Energy Sci. Technol. 47 664 (in Chinese)[蒋勇, 吴健, 韦建军, 范晓强, 陈雨, 荣茹, 邹德慧, 李勐, 柏松, 陈刚, 李理2013原子能科学技术47 664]
[13] Wu J, Lei J R, Jiang Y, Chen Y, Rong R, Zou D H, Fan X Q, Chen G, Li L, Bai S 2013 Nucl. Instrum. Methods Phys. Res. Sect. A 708 72
[14] Iwamoto N, Johnson C B, Hoshino N, Ito M, Tsuchida H, Kojima K, Ohshima T 2013 J. Appl. Phys. 113 143714
[15] Tong W L, Sun Y J, Liu Y H, Zhao G J, Chen Z Z 2015 J. Shanghai Normal Univ. (Nat. Sci.) 44 430(in Chinese)[童武林, 孙玉俊, 刘益宏, 赵高杰, 陈之战2015上海师范大学学报(自然科学版) 44 430]
[16] Liu J, Hao Y, Feng Q, Wang C, Zhang J C, Guo L L 2007 Acta Phys. Sin. 56 3483 (in Chinese)[刘杰, 郝跃, 冯倩, 王冲, 张进城, 郭亮良2007物理学报56 3483]
[17] Shur M, Rumyantsev S, Levinshtein M (translated by Yang Y T, Jia H J, Duan B X) 2012 SiC Mareials and Devices, Volume I&Ⅱ (Beijing:Publishing House of Electroics Industry) pp88-92(in Chinese)[Shur M, Rumyantsev S, Levinshtein M主编(杨银堂, 贾护军, 段宝兴译) 2012碳化硅半导体材料与器件(北京:电子工业出版社)第88–92页]
[18] Zha G Q, Wang T, Xu Y D, Jie W Q 2013 Physics 42 862 (in Chinese)[查钢强, 王涛, 徐亚东, 介万奇2013物理42 862]
[19] Bertuccio G, Casiraghi R 2003 IEEE Trans. Nucl. Sci. 50 175
[20] Lees E J, Bassford J D, Fraser W G, Horsfall B A, Vassilevski V K, Wright G N, Owens A 2007 Nucl. Instrum. Methods Phys. Res. Sect. A 578 226
[21] Jiang Y, Fan X Q, Rong R, Wu J, Bai S, Li L 2012 Nucl. Electron. Detect. Technol. 32 1372 (in Chinese)[蒋勇, 范晓强, 荣茹, 吴建, 柏松, 李理2012核电子学与探测技术32 1372]
[22] Mandal C K, Chaudhuri K S, Nguyen V K, Mannan A M 2014 IEEE Trans. Nucl. Sci. 61 2338
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