碳化矽的奈米晶體是近期量子點研究的熱門材料之一。其中讓高溫矽基板接觸碳氫化合物氣體是常被用於製備碳化矽奈米晶體的方式，然而碳化矽成長機制的細節仍舊不明朗。這裡我們以STM研究Si(111)-7x7表面初始碳化，樣品製備方式是將高溫Si(111)-7x7樣品暴露於離子槍運作時釋出的氣體。RGA數據的分析結果顯示，離子槍去氣時釋出的氣體主要由H2、C2Hx和CO2組成。經過碳化的Si(111)-7x7樣品長出了碳化矽顆粒、單層原子深的凹陷和三種二維結構，因為碳化矽顆粒並非最先生成的產物，我們將聚焦在二維的結構上。這些二維結構透過STM影像及FFT分析得知，(√3x√3) R30°表面重構主要出現在terrace上，少部分的比例出現在凹陷區域內；這種結構最早被發表在乙炔碳化Si(111)-7x7的文獻中。另外兩種結構是3x3和6x6，大部分的6x6結構出現在台階邊緣，少部分出現在terrace凹陷區域內；3x3結構只出現在台階邊緣的凹陷區域內。我們也發現當暴露劑量加倍時， (√3x√3) R30°凹陷處長出了新生的碳化矽顆粒。

The grains of SiC nanocrystal are one of the hot issue of quantum dot research in recent years. One of the popular methods to form SiC grains is the carbonization of silicon substrates by means of hot reaction with hydrocarbon gases. Though SiC nanocrystals can be fabricated by this method, the SiC formation mechanism is still not so clear so far. In this STM study, the gases released from ion gun were used as reactants to carbonize hot Si(111)-7x7 surfaces in order to investigate the early stage of carbonization. From the analysis of RGA data, the gases released from ion gun in its degas mode were mainly H2, C2Hx, and CO2. After the carbonization, SiC grains, mono-layer deep craters, and three two-dimensional (2D) structures were formed on the Si(111)-7x7 surface. Because the SiC grains would not be the first product in the carbonization process, we focus on the 2D structures. These structures were determined by STM images and FFT analysis. The (√3x√3) R30° reconstruction mainly appearing on terraces has a dominated proportion of reacted area. A fraction of them appear on some crater bottoms. This reconstruction is reported to be the first structure when hot Si(111)-7x7 surfaces react with C2H2. The other two structures were 3x3 and 6x6. Most 66 regions appear on the step edges, the others show up on the terraces. The 3x3 structure only appears in the bottom of craters next to the step edges. We also found that SiC grains grow in the crater bottom of (√3x√3) R30° when the dosage of gases is doubled.

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