基于Voigt函数拟合的离子激发发光光谱分峰方法

离子激发发光(IBIL)分析作为一种实时原位的光谱分析技术，由于其对样品内部结构的敏感性，给我们分析样品光谱谱峰信息带来了一定的困难。为了准确地对离子激发发光能谱进行分峰以便更加清晰地判断材料内部不同缺陷的发光中心，提出了一种利用Voigt函数，通过L-M（levenberg-marquardt）非线性最小二乘算法对100和200 K温度时ZnO的IBIL能谱中深能级发射（DBE）峰进行分峰的方法。通过对比Gauss函数和Voigt函数对能谱拟合后峰位随注量的波动情况，发现使用Voigt函数拟合得到的峰位更加稳定，并且收敛速度更快。同时通过对使用Voigt函数拟合后得到的峰中心位于1.75, 1.95和2.10 eV三个子峰的高斯函数半高宽与洛伦兹函数半高宽比较，发现洛伦兹函数半高宽约为高斯函数半高宽的1/10，而且100 K时的1.95 eV峰，200 K时1.75和1.95 eV峰，其洛伦兹峰半高宽数值为10-10量级以下，说明其中非均匀展宽（高斯展宽）仍然是谱峰展宽的主要机制；而电子与声子散射作用是洛伦兹展宽的主要机制。对于涉及导带中大量电子的2.10 eV子峰，其在200 K时洛伦兹函数半高宽明显大于100 K时，由于在温度较高时，由于晶格热振动加剧，且电子热运动加强，增大了散射概率，导致电子与声子的散射作用加强，从而对洛伦兹谱线进一步展宽。而峰中心位于1.75 eV的红光，其主要与V_Zn相关，在100 K时其子峰的洛伦兹半高宽为0.02 eV, 但在200 K时变得极小，这可能是由于100 K时V_Zn束缚的电子或激子在200 K获得足够的热动能摆脱了V_Zn束缚，减弱了与周围的晶格的散射作用，从而使得洛伦兹展宽变得极弱。实验结果表明Voigt函数更加适用于IBIL能谱拟合分峰，这也为以后IBIL技术应用于其他材料内部结构能谱分析提供了可借鉴的依据。

Peak Splitting Method of Ion-Beam-Induced-Luminescence Spectrum Based on Voigt Function Fitting

Ions beam-induced luminescence(IBIL) analysis is a real-time in-situ spectroscopy technique. Due to its sensitivity to the internal structure of the sample, it brings us certain difficulties in analyzing the spectral peaks information of the sample. In order to more accurately split the peaks of the IBIL energy spectra to more clearly determine the luminescence centers of different defects of the material, this paper proposes a Voigt function based on the LM (Levenberg-Marquardt ) of non-linear least squares algorithm to split the deep band emission peaks in the IBIL energy spectra of ZnO at 100 and 200 K. By comparing the fluctuation of the position of the peak with fluence after the Gauss function and the Voigt function are fitted to the energy spectrum, it is found that the position of the peak obtained by the Voigt function fitting is stable and the convergence speed is fast. At the same time, by comparing the full width at half maximum (FWHM) of the Gaussian function with the FWHM of the Lorentz function of the three sub-peaks of 1.75 , 1.95 and 2.10 eV after fitting using the Voigt function, it is found that the FWHM of the Lorentz function is about 1/10 of FWHM of the Gaussian function. Moreover, the 1.95 eV peak at 100 K, 1.75 and 1.95 eV peak at 200 K, the FWHM of the Lorentz peak is below the order of magnitude, indicating that the non-uniform broadening ( Gaussian broadening) is still the main mechanism of spectral peak broadening; while the scattering of electrons and phonons is the main mechanism of Lorentz broadening. For the 2.10 eV sub-peak involving a large number of electrons in the conduction band, the FWHM of the Lorentz function at 200 K is significantly greater than 100 K, and the thermal vibration of the crystal lattice is intensified at a higher temperature, and the thermal movement of electrons is strengthened. It increases the probability of scattering, strengthening the scattering effect of electrons and phonons, further broadening the Lorentz spectrum. The red light with the peak center at 1.75 eV is mainly related to V_Zn. At 100 K, the FWHM of this is 0.02 eV, but it becomes extremely small at 200 K. This is because bound electrons or excitons get enough thermal kinetic energy at 200 K to get rid of the V_Zn bond, weaken the scattering effect with the surrounding lattice, so that the Lorentz broadening becomes extremely weak. The experimental results show that the Voigt function is more suitable for IBIL energy spectrum fitting to split peaks, which also provides an example for the future application of IBIL to the energy spectrum analysis of the internal structure of other materials.