刻蚀方式对金标准物质逸出功测量的影响

Effect of Etching Methods on Measurement of Work Function for Gold Reference Materials

为了避免设备未合适校准带来的测量误差,在紫外光电子能谱(UPS)测试前进行标准物质逸出功(WF)的校准,对获得准确可靠的WF参考值至关重要.高纯金片(Au)性能稳定且具有清晰的费米边,是用于WF以及费米能级校准较为便利的标准参考物质.但是由于表面吸附及污染的存在,需要对Au标准物质进行离子刻蚀处理.采用不同的刻蚀方式对WF测量的影响进行研究,结果表明,栅格扫描刻蚀和定点刻蚀的方式不仅影响UPS测试谱图的质量,且随着刻蚀结束后停留时间的增加,分析室内的残余杂质分子会逐步吸附在Au表面,引起其WF的降低.同时由于定点刻蚀后表面不均匀性较大,有效刻蚀区域WF的平均值与标准值的相对误差达到10.48%.为保证UPS测量结果的准确性,建议在刻蚀完成后尽快进行WF测量.虽然栅格扫描刻蚀所使用时间较长,但是对样品的清洁效果以及测试的质量总体要优于定点刻蚀.

To avoid measurement errors caused by improper calibration of the equipment,it is necessary to calibrate the work function(WF)of the reference material before performing an ultraviolet photoelectron spectroscopy(UPS)test to ensure that the WF reference values are accurate and reliable.High purity gold samples with stable chemical properties and clear Fermi edge,serve as standard reference material for calibrating WF and the Fermi level.However,Au reference materials are subject to surface adsorption and contamination and must be ion etching treatment.The effect of different etching methods on the WF measurement of Au reference materials in UPS measurement was studied.The results showed that the different sputtering methods,raster scan etching and fixed-point etching,not only affected the quality of UPS spectra but also led to a decrease in WF as residual impurities in the analysis chamber environment gradually adsorbed onto the Au surface with increasing dwell time after etching.Additionally,due to the greater surface inhomogeneity after fixed-point etching,the relative error between the mean value and the standard value of the WF in the effective etching reached 10.48%.To ensure the accuracy of UPS measurements,it is recommended that WF be measured as soon as possible after etching.Raster scan etching took more time than fixed-point etching,but sample cleaning effect and spectral quality were generally better.