鎵在鍺(100)表面上的不尋常成長過程與其原子模型

本研究中，利用掃描式穿隧電子顯微技術來探討鎵在鍺(100)上的鍵結模式及表面形貌。常溫下，少量的鎵原子在鍺表面上往 [110] 方向成長形成長鏈狀，隨著沉積量的增加鎵原子開始往 [-110] 方向成長，有如一塊塊的鎵小島在鍺表面上展開。當沉積量達0.5 ML時鎵在鍺表面上的結構為2 × 2，若再增加覆蓋量則鎵原子將以三維團簇的形式堆疊在2 × 2上。此成長模型如同鎵在矽(100)上成長一般。不同於室溫下的成長模式，當鍺(100)樣品保持在300 ˚C下沉積鎵原子，其成長模式很特別。我們利用在不同偏壓下有不同的電子雲狀態密度，成功地找出鎵原子的隱身之處，發現鎵原子會在鍺的SA階梯邊緣處置換掉鍺原子。因此我提出了一個模型來解釋此鎵原子與鍺原子間的交互作用。在300 ˚C下鎵原子會有規律性的置換掉鍺原子並造成表面鍺的雙原子單體缺陷，隨著鎵原子的沉積量增加鍺的表面缺陷面積也會增加，就像負的島嶼在表面上快速成長一般，除此之外鍺的階梯邊緣處變得崎嶇不堪。在大於0.5 ML下鎵原子會在鍺上形成有序的小島嶼結構8 × n ( n = 4, 5 )並在沉積量大於4 ML之後鎵原子會與鍺原子形成合金。

關鍵字

鎵在鍺(100)表面上的成長

並列摘要

In this study, we use the STM to explore the Ga growth mode on the Ge(100) surface. A small amount of Ga atoms develop like a chain on Ge surface along [110] direction in room temperature. With the deposition of Ga is increasing, Ga atoms will grow along [-110] direction, spreading like islands on the Ge(100). Until the deposition is 0.5 ML, the Ga atoms is 2 × 2 structure on the surface. When the deposition is over 0.5ML, the Ga clusters will appear. In the room temperature, the Ga/Ge(100) model is the same as Ga/Si(100) model. Unlike the Ga/Ge(100) growth mode at room temperature, the Ge(100) was kept at 300 ˚C and deposited Ga atoms is a special phenomenon. We find the Ga atoms which hide on the edge of SA by using the different voltage which have different density of state. We propose a model to explain how’s the interaction between Ga and Ge atoms. At 300 ˚C, Ga atoms will take off and displace the Ge dimer regularity. After increasing the Ga atoms, the surface defect will increase, spreading like a negative island. In addition, the step edge of Ge become rough. When the deposition is great than 0.5 ML, the Ga island arrange on the surface orderly, which structure is 8 × n ( n= 4, 5 ). The Ge and Ga become alloy after the deposition is 4 ML.