核心層光電子激發術對化學氣相沈積法在Si(111)-7x7與Ge(100)-2x1表面上成長磷薄膜現象的研究

Abstract

本論文研究以化學氣相沈積法在Si(111)-7×7與Ge(100)-2×1表面上吸附phosphine (PH3)及成長磷薄膜的現象。實驗方法是以同步輻射光為光源研究P 2p、Si 2p與Ge 3d的核心層光電子激發能譜。研究的結果顯示，室溫下PH3的曝氣量超過20L時，Si(111)-7×7表面即達飽和吸附，此時磷原子覆蓋率達0.14ML。將飽和吸附了PH3(a)的Si(111)-7×7表面加熱至高溫觀察其熱反應變化。溫度在300K到463K之間時，吸附在Si(111)-7×7表面上的PH3(a)會分解成PH2(ads)+H(ads)。而在溫度大於463K時，所有的PH3(a)完全分解，此時PH2(a)亦分解形成Si-P與Si-H。當溫度超過783K時，H會以H2(g)的形態離開表面。加熱溫度大於950K時，表面上的P原子會形成P2(g)從表面脫附。高溫成長磷薄膜的成長溫度為853K時，Si(111)表面的P原子覆蓋率達到最大值0.7ML。在Ge(100)-2×1表面上也對相同的實驗過程做了研究並與Si(111)-7×7表面比較，雖然Si(111)-7×7與Ge(100)-2×1表面的原子排列與重構不同，PH3吸附在Ge(100)-2×1表面後的加熱反應過程大致上與Si(111)-7×7表面類似。

This thesis describes the investigation of the adsorption and decomposition of phosphine (PH3) and the growth of phosphorus on the Si(111)-7×7 and Ge(100)-2×1 surfaces. The experimental method employed is high-resolution core-level photoemission using synchrotron radiation as the photon source. The PH3 molecules adsorb on the Si(111)-7×7 surface and form PH3(a) and PH2(a) radicals at room temperature. More than 20L of PH3 chemisorb on the Si(111) surface at 300K causes a saturated surface with phosphorus coverage of 0.14ML. Annealing the PH3(a)-saturated surface to the temprature range of 300K-463K, the adsorbed PH3(a) radicals dissociate to form PH2(ads)+H(ads). At 463K, PH2(a) radicals dissociate to form P and H radicals. Annealing to higher temperatures causes H2(g) desorption at 783K and P2(g) desorption at 950K. The growth of phosphorus on Si(111) depends on the substrate temperature. The phosphorus coverage results in the maximum of 0.7 ML at 853K. The overall thermal reactions of PH3(a) on Ge(100) and Si(111) surfaces are similar, although the atomic structure and the dangling bond arrangement of the two surfaces are quite different.