紅熒烯與矽（100）混成介面形成對鈷薄膜結構與磁特性之影響

Structures and Magnetic Properties of Co Films Grown on Rubrene-Si (100) Hybrid Interfaces

張丞勛(Tony Cheng-Hsun Chang) ； 許智瑜(Chih-Yu Hsu) ； 蔡志申(Jyh-Shen Tsay)

《真空科技》 27卷2期 (2014/06) Pp. 65-70

摘要

本研究中比較三種異質介面對鈷薄膜成長的結構與磁特性之影響。在矽（100）單晶的表面濺鍍成長鈷薄膜，可以發現當厚度超過80奈米時，利用原子力顯微鏡可以觀察到許多三角錐形狀的特殊表面形貌，透過X光繞射鑑定，此形貌的晶體結構為六方最密堆積，同時從磁滯曲線可以觀察到其方正度都接近一且不受厚度影響。引入紅熒烯當作中介層，由於鈷成長在紅熒烯介面上僅能形成顆粒，無法探測到其六方最密堆積的結構，導致其方正度並無上述之特性。經過退火處理的紅熒烯／矽（100）混成介面，可以使鈷厚度在20奈米就能產生六方最密堆積結構，同時其方正度都不受鈷厚度影響且接近一，呈現出單一磁化易軸以及單一磁域的特性。將矯頑力的大小從高至低排列，其順序皆為鈷／矽（100）、鈷／混成介面、鈷／紅熒烯介面，由於紅熒烯介面表面自由能較低，可以產生緩衝的作用使介面處較為平坦，因此在均勻的紅熒烯分布下緩衝程度較高，使得磁域較連續且缺陷數量較低，造成矯頑力降低。

關鍵字

鈷 ； 紅熒稀 ； 磁性 ； 顯微術 ； 繞射

並列摘要

Structures and magnetic properties of Co films grown on different interfaces containing Si and rubrene have been investigated by employing atomic force microscopy, x-ray diffraction and magneto-optic Kerr effect techniques. On pure Si (100), Co films thicker than 80 nm are observed to be pyramid-like nanostructure corresponding to hcp-Co (hexagonal closed-package) structure as confirmed by x-ray diffraction. For Co on rubrene/Si (100), separated Co clusters are found without the formation of hcp structure. After annealing treatments at 550 K for rubrene/Si (100), rubrene molecules nucleate to form clusters and pinholes develop in the rubrene layer. For Co on annealed rubrene/Si (100), the formation of a Co/Si (100) interface is important for the occurrence of the pyramid-like nanostructure with an hcp stacking of the Co layer. For Co on Si (100) and annealed rubrene/Si (100), the enhancement of the coercive force is attributed to the imperfection introduced by rough interface to impede the magnetization reversal. As the Co thickness increases from 10 to 40 nm on rubrene/Si (100), the squareness increases from 0.9 to near unity. For Co deposited on Si (100) and annealed rubrene/Si (100), the squareness of magnetization curve is close to unity for all the Co thicknesses. The formation of Co islands in hcp structure plays an important role on the enhancement of the squareness of magnetization curve for Co overlayers.

並列關鍵字

Cobalt ； Rubrene ； Magnetic ； Microscope ； Diffraction