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较为全面地考查了非晶硒对 X射线的灵敏度。引入一个灵敏度模型 ,在灵敏度与载流子迁移特性、光子能量、非晶硒厚度和场强之间建立了明确的关系。计算结果表明 ,载流子迁移长度至少应是非晶硒厚度的 2倍以上 ,才能使 X射线激发的电子、空穴有较大的概率到达收集电极 (或非晶硒自由表面 ) (即信号收集效率 ) ;用加大非晶硒厚度的方法增加灵敏度时必须考虑信号收集效率降低的负面影响 ;场强对灵敏度有重要影响 ,提高场强可使非晶硒灵敏度显著增加。改变场强是调节灵敏度的有效方法。
A more comprehensive examination of the sensitivity of amorphous selenium X-ray. A sensitivity model is introduced that establishes a clear relationship between sensitivity and carrier mobility, photon energy, amorphous selenium thickness, and field strength. The calculated results show that the mobility of carriers should be at least twice that of amorphous selenium so that the electrons and holes excited by X-ray can reach the collecting electrode (or the free surface of amorphous selenium) with a high probability (that is, the signal collecting Efficiency). Increasing the sensitivity by increasing the thickness of amorphous selenium must take into account the negative effect of decreasing signal collection efficiency. Field strength has an important influence on sensitivity. Increasing the field strength can significantly increase the sensitivity of amorphous selenium. Changing the field strength is an effective way to adjust the sensitivity.