矽烯與二氧化鉿接面之第一原理計算

Abstract

隨著傳統矽基金氧半場效電晶體逐漸接近其微縮極限，尋找替代超薄通道材料成為現階段迫切的課題。矽可形成二維單原子層，有著與石墨烯相似的結構稱矽烯(Silicene)，獨立矽烯在理論計算中具有超高載子遷移率和可控制能隙，使其成為理想的超薄通道材料。更重要的是，因其與現今矽電子元件同元素，在與現今矽塊材電極整合時，擁有零介面汙染的獨特優勢。 在進行矽烯元件開發時，如何將矽烯生長於絕緣基板上會是很重要的問題，因此在本研究中我們選擇了高介電質氧化物二氧化鉿，並與矽烯接面，以第一原理模擬計算，透過將中、高階的近似理論相互比對；其中高階法我們所採用的是GW 近似，而中階法我們則嘗試了局域密度近似、廣義梯度近似、雜化泛涵法。我們以二氧化鉿(111)面來模擬接面結構，尋找矽烯在何種二氧化鉿原子截止面上，仍能保持超高遷移率並打開合理的能隙值。期待本計算研究的結果，能成為二維通道材料電晶體之產品實現的奠基石。

As the traditional silicon-based metal oxide semiconductor field-effect transistors approaching its miniaturization limit, search of alternative ultra-thin channel materials becomes an urgent issue. Silicon can form a two-dimensional single atomic layer, called “Silicene”. It has a graphene-like structure as well as in theoretical calculations both superhigh carrier mobility and controllable energy gap. These make it an ideal ultra- thin channel material. Moreover, with elements same as the present silicon electronic devices, it has a great advantage of zero interfacial contamination when being integrated towards the silicon-bulk leads. It is important to know how to grow silicene on an insulating substrate in the developments of silicene-based devices. In this work we choose the high dielectric material hafnium oxide to be the substrate and perform first-principles calculations at middle and high levels of approximation to crosscheck, where the high level refers to the GW approximation and the middle to the local density approximation, generalized gradient approximation, and hybrid functionals. We choose the hafnium oxide(111) surface to be substrate and look for its particular surface termination atomic layer that can preserve silicene’s superhigh mobility and open up a reasonable bandgap. We expect that this computational study can become the foundation of realizing an on-market transistor with a two-dimensional channel.