방사선 노출에 따른 3T APS 성능 감소와몬테카를로 시뮬레이션을 통한 픽셀 내부 결함의 비교분석
A Comparison between the Performance Degradation of 3T APS due to Radiation Exposure and the Expected Internal Damage via Monte-Carlo Simulation
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The trend of x-ray image sensor has been evolved from an amorphous silicon sensor toa crystal silicon sensor. A crystal silicon X-ray sensor, meaning a X-ray CIS (CMOS image sensor),is consisted of three transistors (Trs), i.e., a Reset Transistor, a Source Follower and a SelectTransistor, and a photodiode. They are highly sensitive to radiation exposure. As the frequencyof exposure to radiation increases, the quality of the imaging device dramatically decreases. Themost well known effects of a X-ray CIS due to the radiation damage are increments in the resetvoltage and dark currents. In this study, a pixel array of a X-ray CIS was made of 20×20 pixelsand this pixel array was exposed to a high radiation dose. The radiation source was Co-60 andthe total radiation dose was increased from 1 to 9 kGy with a step of 1 kGy. We irradiated thesmall pixel array to get the increments data of the reset voltage and the dark currents. Also, wesimulated the radiation effects of the pixel by MCNP (Monte Carlo N-Particle) simulation. Fromthe comparison of actual data and simulation data, the most affected location could be determinedand the cause of the increments of the reset voltage and dark current could be found.
Abstract
The trend of x-ray image sensor has been evolved from an amorphous silicon sensor toa crystal silicon sensor. A crystal silicon X-ray sensor, meaning a X-ray CIS (CMOS image sensor),is consisted of three transistors (Trs), i.e., a Reset Transistor, a Source Follower and a SelectTransistor, and a photodiode. They are highly sensitive to radiation exposure. As the frequencyof exposure to radiation increases, the quality of the imaging device dramatically decreases. Themost well known effects of a X-ray CIS due to the radiation damage are increments in the resetvoltage and dark currents. In this study, a pixel array of a X-ray CIS was made of 20×20 pixelsand this pixel array was exposed to a high radiation dose. The radiation source was Co-60 andthe total radiation dose was increased from 1 to 9 kGy with a step of 1 kGy. We irradiated thesmall pixel array to get the increments data of the reset voltage and the dark currents. Also, wesimulated the radiation effects of the pixel by MCNP (Monte Carlo N-Particle) simulation. Fromthe comparison of actual data and simulation data, the most affected location could be determinedand the cause of the increments of the reset voltage and dark current could be found.
참고문헌 (7)
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