覆鉑、銠於鉬針形成金字塔單原子針尖之研究

Abstract

本實驗藉由場離子顯微鏡研究覆鉑鉬針及覆銠鉬針，在加熱退火後的皺化行為。覆鉑鉬針實驗中發現，加熱退火溫度在800K以下，針尖上的各指數面，並無明顯變化。在加熱退火溫度超過800K，可觀察到通道面的擴張行為。當加熱退火溫度達到900K，{211}切面劇烈的擴張並造成明顯的皺化行為，加熱退火至1100K金字塔稜線已經明顯形成，並且可成長出單原子級針尖，其最上方三層的金字塔結構分別為1、3、10及1、6、15顆原子的堆疊。 在覆銠鉬針的實驗中發現，在加熱退火溫度至1100K時，同樣可以成長出單原子級針尖，其最上方三層的金字塔結構分別為1、3、10及1、6、15顆原子的堆疊。 藉由覆鉑鉬針可以研究多稜線現象的行為，在加熱退火至800~900K可以觀察到多稜線現象的產生，金字塔稜線數目隨著加熱退火溫度逐漸下降，在加熱退火溫度接近900K時，則收斂至三對稱的單條稜線。Faceting phenomena had been studied for both Pt-covered Mo tip and Rh-covered Mo tip by field ion microscope. The results of the Pt-covered and Rh-covered Mo tips were similar. Faces between {110} and {211} faces expanded with increasing annealing temperature at the temperature ranging from 800 K to 900 K. The {211} faces started to expand at 900 K, and the area of {211} faces reached maximum at 1100 K. Three expanding {211} faces resulted in the formation of three crest lines. A single atom was discovered among the three crest lines, and the pyramidal single atom tip was formed. The stacking of the pyramidal single atom tips was 1, 3, 10 or 1, 6, 15. On the other hand, we studied the hill and valley faceting phenomena of Pt-covered Mo tips samples. The hill and valley faceting was observed at the annealing temperature between 800 K and 900 K. The number of crest lines decreased with increasing annealing temperature. The branch of crest lines converged at single crest line at 900 K.