Infrared optical properties of diamond films and electrical properties of CVD diamond detectors
Infrared optical properties of diamond films and electrical properties of CVD diamond detectors
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DOI：
10.1088/0022-3727/36/20/019
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发表时间：
2003-10
期刊：
影响因子：
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通讯作者：
Linjun Wang;Yiben Xia;Hujiang Shen;Minglong Zhang;Ying Yang;L. Wang
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文献类型：
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作者：
Linjun Wang;Yiben Xia;Hujiang Shen;Minglong Zhang;Ying Yang;L. Wang
本文首次用红外椭圆偏振光谱法研究了用微波等离子体化学气相沉积（MPCVD）方法在硅衬底上生长的金刚石薄膜的红外光学性质。利用退火处理对金刚石薄膜消光系数k和折射率n的影响，在N2气氛中进行热退火处理可以显著提高金刚石薄膜的红外光学质量。退火后，k值约为10−12-10−15。然而，对于未退火的金刚石膜，k值在很大范围内变化，约为10−3-10−14。退火后的金刚石膜的折射率n增加，接近于单晶，IIa型天然金刚石。金刚石膜在H_2O_2和H_2SO_4溶液中进行表面氧化处理后，金刚石表面的石墨在一定程度上被去除，使CVD金刚石探测器的漏电流明显降低。基于这些金刚石薄膜，金刚石x射线探测器的响应时间约为3 ns的制作。从CVD金刚石探测器的温度行为和时间响应的X射线照射，我们发现，存在于膜中的各种缺陷或杂质可能是负责长的下降时间。
In this paper, the infrared optical properties of diamond films grown on silicon substrates by means of the microwave plasma chemical vapour deposition (MPCVD) method were first studied by infrared spectroscopic ellipsometry in the photo energy range of 0.1–0.4 eV. Using the effects of annealing treatment on the extinction coefficient k and refractive index n of diamond films, the infrared optical quality of the diamond film can be significantly improved by thermal annealing treatment in N2 atmosphere. After annealing the value of k was about 10−12–10−15. However, for the non-annealed diamond film, the value of k varied in a large range, about 10−3–10−14. After annealing the refractive index n of the diamond film increased and was close to that of a single crystal, Type IIa natural diamond. The graphite on the diamond surface can be removed to some extent after surface oxidizing treatment of the diamond film in a solution of H2O2 and H2SO4, which causes the obvious decrease of the leakage current of the CVD diamond detector. Based on these diamond films, diamond x-ray detectors with a response time of about 3 ns were fabricated. From the temperature behaviour and the time response of the CVD diamond detector to x-ray irradiation, we find that the various defects or impurities that exist in the film may be responsible for the long fall time.