Characterization of gallium arsenide X-ray mesa p-i-n photodiodes at room temperature
Characterization of gallium arsenide X-ray mesa p-i-n photodiodes at room temperature
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DOI：
10.1016/j.nima.2015.12.030
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发表时间：
2016-03
影响因子：
1.4
通讯作者：
G. Lioliou;X. Meng;J. Ng;A. M. Barnett
中科院分区：
文献类型：
--
作者：
G. Lioliou;X. Meng;J. Ng;A. M. Barnett
本文报道了两个用于光子计数X射线光谱学的GaAs mesap ~+-i-n ~+光电二极管（厚度为7 μm，直径为200 μm）在580 ~ 980 nm波长范围内的响应特性和其中一个在室温下探测软X射线的性能。暗电流和电容测量作为施加正向和反向偏置的函数。结果表明，在最大内电场（22 kV/cm）下，漏电流密度在nA/cm 2范围内。根据电容测量结果计算，该层的非故意掺杂浓度<1014 cm −3。在可见光和近红外光照射下对两种二极管进行光电流测量。对这些测量结果的分析表明，在p+侧顶部接触界面处存在非活性（死）层（0.16 μm厚），其中光生载流子对光电流没有贡献，可能是由于复合。其中一个二极管D1也被表征为室温光子计数X射线光谱的探测器;在5.9 keV处实现的最佳能量分辨率（FWHM）为745 eV。基于在不同成形时间和施加的反向偏置获得的频谱，对系统的噪声分析表明，噪声的主要来源是介电噪声。在0 V时，至少存在（165±24）eV的电荷俘获噪声。
Two GaAs mesap+-i-n+photodiodes intended for photon counting X-ray spectroscopy, having anilayer thickness of 7 μm and diameter of 200 μm, have been characterized electrically, for their responsivity at the wavelength range 580 nm to 980 nm and one of them for its performance at detection of soft X-rays, at room temperature. Dark current and capacitance measurements as a function of applied forward and reverse bias are presented. The results show low leakage current densities, in the range of nA/cm2at the maximum internal electric field (22 kV/cm). The unintentional doping concentration of theilayer, calculated from capacitance measurements, was found to be <1014cm−3. Photocurrent measurements were performed under visible and near infrared light illumination for both diodes. The analysis of these measurements suggests the presence of a non-active (dead) layer (0.16 μm thickness) at thep+side top contact interface, where the photogenerated carriers do not contribute to the photocurrent, possibly due to recombination. One of the diodes, D1, was also characterized as detector for room temperature photon counting X-ray spectroscopy; the best energy resolution achieved (FWHM) at 5.9 keV was 745 eV. The noise analysis of the system, based on spectra obtained at different shaping times and applied reverse biases, showed that the dominant source of noise is the dielectric noise. It was also calculated that there was at least (165±24) eV charge trapping noise at 0 V.