Study of Radiation Damage on Electronic Parts for High Energy Physics

电子部件的辐射损伤将是下一代机器如超导超级对撞机和大型强子对撞机进行高能实验时最严重的问题之一。半导体器件是探测器的重要组成部分，电子器件甚至粒子探测器本身都可能由半导体制成，因此必须对半导体器件的辐射损伤进行系统的研究。在系统研究的开始，我们选择了一种基于平面工艺生产的pn结二极管的硅条探测器（SSD），这是各种微电子器件的基本结构。测试了六种不同类型的SSD。它们有不同的结和绝缘结构；不同尺寸的pn结和结间绝缘，不同厚度的Si <O_2>绝缘子，不同类型的半导体基。12GeV PS抽提质子束在KEK下轰击这些样品，在直径为7mm （FWHM）时，束的瞬时强度约为<10^(11)>质子/s。在束中心处辐照的总剂量测量为2 X <10^(14)>质子/ <cm^2>。通过测量在辐射缺陷处产生的暗电流来评估辐射损伤的量。对辐照后的固态固态观测到<^(241)Am> < γ >射线和穿透性< β >射线信号，并与新辐射的信号进行了比较。在不同结绝缘子结构的6个样品中，暗电流的增加没有明显的差异。已经观察到< γ >射线和< β >射线信号的脉冲高度衰减。当总剂量为5x <10^4> Gy时，降解率为10%。< γ >射线信号能量分辨率下降的主要原因是暗电流增大，产生较大的散粒噪声。

Radiation damage on electronic parts will be one of the most serious problems for a high energy experiment of the next generation machine such as the Superconducting Super Collider and the Large Hadron Collider. We, therefore, must study systematically the radiation damage of semiconductor devices which are the most important parts of detector electronics or even particle detector itself may be made by semiconductor. At start of the systematic study, we picked up a silicon strip detector (SSD) based on a pn junction-diode produced by planer-process which is the basic stracture of every kind of microelectronics.Six different type of the SSD was tested. They have all different junction and insulation structure; different size of pn junction and insulation between junctions, different thickness of Si <O_2> insulator, and different type of semiconductor-base.Extracted-proton-beam of 12GeV PS bombarded on these samples at KEK Instantaneous intensity of the beam was about <10^(11)> protons/s for 7mm (FWHM) diameter. Total dose irradiated at the center of the beam was measured to be 2 X <10^(14)> protons/ <cm^2> . An amount of the radiation damage has been evaluated by measurement of a dark-current which is generated at radiation defects. Also signals of <^(241)Am> <gamma> ray and penetrating <beta> ray has been observed for the irradiated SSD and comapred with signals from new one.No sizable difference in the increase of dark current has been observed between six samples having different junction-insulator structure. Pulse-height degradation for <gamma> ray and <beta> ray signals hasbeen observed. It amounts to 10% degradation for total dose of 5x <10^4> Gy. Degradation of energy resolution for <gamma> ray signal can be mainly explaned by the increase of dark current causing large shot-noise.