开尔文力显微镜检测ZnO薄膜的接触电势差

Kelvin Probe Force Microscopy for Contact Potential Difference Measurement of ZnO Film

本文利用开尔文力显微镜观测了ZnO薄膜上ZnO/Si台阶处的接触电势差,研究了扫描速度对接触电势差检测的影响,并分析了造成这种影响的原因。实验测得电势分布在ZnO/Si台阶处有明显变化,ZnO/Si的接触电势差为250mV。实测值偏离理论计算值的原因是接触电势差受大气中表面吸附、氧化层、表面电荷等因素的影响。在不同的扫描速度下对同一区域进行扫描,发现扫描速度对接触电势差的检测有很大影响,扫描速度增大,检测结果逐渐偏离真实值,这种现象是力调制模式的开尔文力显微镜的信号处理方式造成的。建议在低速下进行扫描,以获得理想的检测结果。

The contact potential difference （CPD） at the boundary of the electrode and substrate in ZnO film is measured using Kelvin probe force microscopy （KFM） and the relationship between measured CPD and scanning speed is studied. The measured CPD of ZnO/Si was 250mV. Due to different work function of ZnO and Si, a steep potential change is observed at ZnO/Si step. Changing the scanning speed, the measured CPD depends deeply on the scanning speed. The bigger scanning speed be, the weaker potential contrast of the image is observed. It is suggested that the scanning speed is limited by the amplitude-sensitive method of KFM. So, lower scanning speed is recommended.