以蝕刻吸附法備製覆銥鎢單原子級針尖與場發射電子電流量測

Abstract

實驗以場離子顯微鏡(FIM)對覆銥鎢單原子針尖量測場發射電子電流。此針尖樣品不以指甲油封針電鍍，改用液面控制法減少銥原子的舖覆量，經加熱處理後，成長出單原子針尖。實驗中發現類型一單原子針尖場增益效果較類型二單原子針尖明顯，在-1800V的電壓下，量測得到電流數值：類型二單原子針大於六原子針尖與三原子針尖。 以回收KOH溶液進行蝕刻後的針尖，此針尖置入真空腔加熱後，可立即成長出單原子級針尖，並以三原子針尖量測約1nA場發射電流，三原子結構依舊穩定。以穿透式電子顯微鏡(TEM)並以光譜分析(EDS)進行成份分析，此針尖明顯有銥原子訊號，證實此蝕刻方法在蝕刻完成後，貴金屬會自然舖覆於鎢針尖。

We use the field ion microscope (FIM) to measured fluctuations of electron emission current from Ir on W single-atom tip(SAT). For electroplating Ir metals, we do not use nail polish to cover the tip. The single-atom can sometime form at the top of the nano-pyramid tip by high temperature annealing. We find that type 1 SAT have higher current than type 2 SAT. At -1800V, the emission current of type 2 SAT is greater than three atoms tip and six atoms tip. An atomic tip was formed by high temperature annealing the tip etched by recycled KOH solution. After the measurement of electron emission about 1nA for three atoms tip, the tip maintains the same structure. Using field-emission transmission electron microscope (TEM) and energy dispersion x-ray spectrometer (EDS) to measure the microstructures and chemical compositions, we can find Ir atoms on the tip surface. It suggests that Ir atoms are deposited on the tip.