場離子顯微鏡研究 (1)量測覆銥單原子針場發射與場離子電流 (2)鈮(100)表面觀察

Abstract

覆銥單晶鎢針經數次加熱退火長成金字塔結構後，以法拉第杯與微通道板量測金字塔結構的場離子電流與場發射電子電流。對場發射電流而言，針形的尖銳度比金字塔結構的影響更大。離子電流的起始電壓是由針型尖銳度影響，飽和離子電流由金字塔結構影響，且發現微通道板量測飽和離子電流時的放大倍率約為法拉第杯量測的5000倍。多晶鈮針在數次加熱退火後，(100)面確實產生皺化。Using Fraday cup and MCP (microchannel plate) measured field emission currents and field ion currents after Ir covered single crystal tungsten tips form pyramid strcture. Tip’s shape affects field emission current more then pyramid strcture. Threshold voltage of field evaporation is affected by sharpness of tip. Satuaration ion current is affected by pyramid structure. Satuaration ion current which is measured with MCP isbigger then satuaration ion current which is measured with Faraday cup 5000 times. Nb {100} can be faceting because Nb{310} expands after annealing.