X-ray-to-current signal conversion characteristics of trench-structured photodiodes for direct-conversion-type silicon X-ray sensor
X-ray-to-current signal conversion characteristics of trench-structured photodiodes for direct-conversion-type silicon X-ray sensor
复制标题
DOI：
10.7567/jjap.56.04ch06
复制
发表时间：
2017-02
影响因子：
1.5
通讯作者：
T. Ariyoshi;S. Funaki;K. Sakamoto;A. Baba;Y. Arima
中科院分区：
文献类型：
--
作者：
T. Ariyoshi;S. Funaki;K. Sakamoto;A. Baba;Y. Arima
为了减少医疗X射线诊断所需的辐射剂量，我们提出了一种高灵敏度的直接转换型硅X射线传感器，使用沟槽结构的光电二极管。该传感器由于其低偏置电压而在其长器件寿命、抗噪性和低功耗方面是有利的。利用该传感器，可以以几乎100%的效率检测X射线;因此，与传统的间接转换型传感器相比，灵敏度可以提高约10倍。在这项研究中，测试芯片采用单多晶硅单金属0.35微米工艺制造。用于X射线传感器的形成的沟槽光电二极管约为170和300 µm深。在25 V的偏压下，吸收X射线到电流信号的转换效率在沟槽深度为170 µm时为89.3%（理论极限; 96.7%），在沟槽深度为300 µm时为91.1%（理论极限; 94.3%）。
To reduce the radiation dose required in medical X-ray diagnoses, we propose a high-sensitivity direct-conversion-type silicon X-ray sensor that uses trench-structured photodiodes. This sensor is advantageous in terms of its long device lifetime, noise immunity, and low power consumption because of its low bias voltage. With this sensor, it is possible to detect X-rays with almost 100% efficiency; sensitivity can therefore be improved by approximately 10 times when compared with conventional indirect-conversion-type sensors. In this study, a test chip was fabricated using a single-poly single-metal 0.35 µm process. The formed trench photodiodes for the X-ray sensor were approximately 170 and 300 µm deep. At a bias voltage of 25 V, the absorbed X-ray-to-current signal conversion efficiencies were 89.3% (theoretical limit; 96.7%) at a trench depth of 170 µm and 91.1% (theoretical limit; 94.3%) at a trench depth of 300 µm.