Development of n+-in-p planar pixel sensors for extremely high radiation environments, designed to retain high efficiency after irradiation-猫眼课题宝

DOI：

10.1016/j.nima.2016.04.039

发表时间：

2016-09

期刊：

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment

影响因子：

1.4

通讯作者：

中科院分区：

物理与天体物理3区

文献类型：

作者：

Y. Unno;S. Kamada;K. Yamamura;Y. Ikegami;K. Nakamura;Y. Takubo;R. Takashima;J. Tojo;T. Kono;K. Hanagaki;K. Yajima;Y. Yamauchi;M. Hirose;Y. Homma;O. Jinnouchi;K. Kimura;K. Motohashi;S. Satō;H. Sawai;K. Todome;D. Yamaguchi;K. Hara;K. Sato;K. Sato;M. Hagihara;S. Iwabuchi

我们已经开发了n+-in-p像素传感器，以获得高度耐辐射的传感器，用于极高的辐射环境，如在高亮度LHC中发现的那些。我们设计了新颖的像素结构，通过将偏置轨移出边界区域并将偏置电阻器布线在像素电极区域内，来消除照射后偏置轨下的效率损失源。在3× 1015 neq/cm 2的质子辐照下，将多晶硅偏置电阻和偏置轨移离边界的像素结构在边界区域的效率损失< 0.5%，与不加偏置结构的像素结构的效率相当。具有在边界处的偏置轨和在偏置轨下方的加宽的p止挡的像素结构还表现出在边界区域处每像素大约1%的改进的损耗。我们已经阐明了背后的物理机制的效率损失偏轨下的TCAD模拟。效率损失是由于用作电荷收集电极的偏置轨与边界处的表面附近的硅中的低电场区域的相互作用。该区域充当电极的“屏蔽”。照射后，强电场几乎消除了该区域。TCAD模拟表明，宽的p-停止和大的Si-SiO2界面电荷（具体地说，反型层）起到屏蔽加权电位的作用。经2.4 MGy γ射线辐照的旧设计像素传感器在边界处仅表现出轻微的效率损失。

We have developed n+-in-p pixel sensors to obtain highly radiation tolerant sensors for extremely high radiation environments such as those found at the high-luminosity LHC. We have designed novel pixel structures to eliminate the sources of efficiency loss under the bias rails after irradiation by removing the bias rail out of the boundary region and routing the bias resistors inside the area of the pixel electrodes. After irradiation by protons with the fluence of approximately 3× 10 15 n eq/cm 2, the pixel structure with the polysilicon bias resistor and the bias rails removed far away from the boundary shows an efficiency loss of< 0.5% per pixel at the boundary region, which is as efficient as the pixel structure without a biasing structure. The pixel structure with the bias rails at the boundary and the widened p-stop's underneath the bias rail also exhibits an improved loss of approximately 1% per pixel at the boundary region. We have elucidated the physical mechanisms behind the efficiency loss under the bias rail with TCAD simulations. The efficiency loss is due to the interplay of the bias rail acting as a charge collecting electrode with the region of low electric field in the silicon near the surface at the boundary. The region acts as a “shield” for the electrode. After irradiation, the strong applied electric field nearly eliminates the region. The TCAD simulations have shown that wide p-stop and large Si–SiO 2 interface charge (inversion layer, specifically) act to shield the weighting potential. The pixel sensor of the old design irradiated by γ-rays at 2.4 MGy is confirmed to exhibit only a slight efficiency loss at the boundary.

Development of n+-in-p planar pixel sensors for extremely high radiation environments, designed to retain high efficiency after irradiation

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