蒙特卡罗法模拟低失能近轴背散射电子能谱

用蒙特卡罗方法模拟计算了薄样品中的高能同轴背散射电子的背散射率和厚度衬度.结果指出用较大的探测能量窗口和大的探测角可在确保厚度衬度的前提下增强信噪比.大的入射能量虽有利于厚度衬度,但不利于提高信噪比.薄膜沉积在异质衬底上的模拟结果显示,虽然背散射率中包含有衬底材料的信息,但还是膜层厚度的单调变化函数,有可能通过背散射率的测量来判定薄膜厚度.

Energy Distribution of the Low Loss Energy and Coaxial Backscattered Electrons,Simulated by Monte Carlo Method

By using the Monte Carlo method, we calculate the energy distribution of the low loss energy and coaxial backscattered electrons. We discuss the influence of primary energy, sample atomic number and detection angle upon the energy distribution. The simulation results show that the value of the elastic diffusion peak decreases and the maximum value of backscattered electron number shifts to lower energy as increasing of primary energy and decreasing of sample atomic number. The detection angle has not influence on the energy distribution. The use of lower primary energy, higher energy windows and detection angle can increase the backscattering coefficient. The greater values of primary energy and lower values of energy windows correspond to greater relative variation of backscattering coefficient; the detection angle has no evident effect on the relative variation of backscattering coefficient. It is useful to use greater value of detection angle for increasing the backscattering coefficient and ameliorating the ratio of signal to noise.