| Summary: | 碩士 === 國立中興大學 === 物理學系所 === 102 === Sample preparation for scanning capacitance microscopy (SCM) significantly influences the accuracy of SCM measurements. Especially, the quality of the oxide layer on sample surface including surface roughness of the oxide layer, interface traps, and charges in the oxide layer is decided by sample preparation. These factors influencing the oxide qualities induce capacitor-voltage curve distortion and shift, and hence lead to exceptional differential capacitor (dC/dV) signal intensity. In this article, a short-wavelength semiconductor laser was employed to investigate the improvements of irradiation treatment on the surface oxide layer of a silicon substrate. The specimens were treated by laser illumination with different power and duration. With scanning capacitance spectroscopy (SCS), one can observe the changes in the stability of the surface oxide layers. Experimental results indicated that increasing the illumination power improves the quality of the surface oxide layer, resulting in dC/dV curves with a small flat-band voltage shift and higher signal intensities. Changing the illumination duration leads to changes in the full width at half maximum (FWHM) of SCS curves, but flat-band voltage shift. The main influence of illumination duration is to reduce the trapped charges in the surface oxide layer. For the sample preparation without illumination treatment, the SCS curves of the samples exhibited a high flat-band shift, implying that there are more oxide defects, i.e., low oxide quality. This results in low dC/dV signal intensities. The experimental approach provides a reference for enhancing the dC/dV signal intensities and the stability of SCM measurements on the micro-analysis of electronic materials and surface/interface analysis.
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