基于共振拉曼光谱的ZnO薄膜载流子浓度提取

Carrier Concentration Determination in ZnO Thin Film based on Resonant Raman Spectroscopy

研究了共振拉曼散射在ZnO材料载流子浓度探测方面的应用。实验发现在可见光激发下,原有模型受限于激光穿透深度和耦合模强度,并不能很好的进行ZnO薄膜的载流子浓度探测,且在紫外光激发下,1LO模的移动规律出现异常。为此,研究分析了1LO过程的产生机制,并基于级联模型理论将其异常的移动行为归因子晶体缺陷。结合2LO过程不受晶体缺陷浓度影响的特点,研究建立起了运用2LO模分析ZnO载流子浓度的方法,并对各电子浓度的ZnO样品进行测试。拟合结果发现该方法在高载流子范围(>1019cm-3)与霍尔结果吻合较好。

The application of resonant Raman spectroscopy in carrier concentration determination in ZnO was investigated in this paper.The restriction of visible excitation in this application was on penetration depth and coupled mode intensity.While under ultraviolet excitation,the abnormal behavior of 1LO modes was investigated and its origin was attributed to the defects in the crystal,which was explained in the cascade model.We substituted the 1LO-based method with the 2LO-based one and tested various ZnO samples under the new method.The fitting result shows that under resonant Raman conditions,carrier concentration obtained from Raman spectrum has great consistency with Hall results in high carrier concentration region.