三族氮化物在矽基板上與氮化鈧與石墨烯之異質界面研究

Study of III-nitride semiconductor heterostructures with ScN and graphene on silicon substrate

許紘瑋(Shiu, Hung Wei)

指導教授 ： 果尚志 ； 陳家浩

國立清華大學/理學院/物理學系/博士(2014年)

摘要

由於三族氮化物在光學電子元件的應用上具有極優良的電子與光學特性，因此一直以來都備受關注。然而，三族氮化物在實際元件的應用上仍有許多問題需要克服，如自發極化場，應力誘發之壓電場，基板效應以及異質界面問題等。於本文，我們將討論兩種特別的材料−氮化鈧與石墨稀−並討論它們與氮化鎵之間的異質接合關係。由於氮化鈧為一非極化材料，且過去的文獻指出，氮化鈧的晶格排列與氮化鎵完美匹配，因此如能使用氮化鈧作為成長氮化鎵時的緩衝層，將可進一步的提升氮化鎵的品質。而石墨稀則更令人興奮，因為它具有極佳的光穿透率與電子特性，因此人們相信，它在另外三族氮化物光學電子元件的穿透電極的應用上，是極具潛力的。除了這兩種異質介面研究外，三族氮化物的本質特性研究也極為重要，尤其是具有極特殊表面效應的氮化銦。因此，了解並探討三族氮化物的本質與異質介面研究是極讓人感興趣的。
在第一章，我們將簡單介紹三族氮化物，稀土族與過度元素的基本特性，並將簡述石墨稀引人注目的電子與光學特性與其在元件上的應用。第二章將簡述本文研究所使用的相關儀器與設施。而第三章我們將分兩個部分來討論氮化鈧與氮化鎵的異質介面研究。由於過去的文獻指出，當氮化鈧成長於矽基板時，些許的矽化鈧會產生。因此，在第一小節我們將討論矽化鈧的形成與特性，並在第二小節探討氮化鈧的結構與特性以及與氮化鎵的異質界面效應。第四章討論石墨稀的層數與氮化鎵之間的電子光學特性的關聯性。而在第五章，我們針對原位成長的氮化銦來討論它的基本性質，希望能解出氮化銦表面電子累積的成因。最後在第六章，針對本文的內容做出總結，與期望。

關鍵字

III-nitride ； Schottky barrier ； graphene ； photoemission ； Rare-earth

並列摘要

III-nitride semiconductors have attracted a lot of attention due to its outstanding electronic and optical properties for the application of optoelectronic devices. However, several effects strongly influence the performance of the III-nitride based devices, including natural spontaneous polarization, strain induced piezoelectric polarization, the substrate effects and heterostructure with other materials. In this study, two special materials for the heterostructures with GaN were introduced, one is ScN and the other is graphene. ScN is a non-polar material and its lattice parameter is excellently matched with GaN, using ScN as a buffer layer for growing GaN will definitely enhance the quality of GaN. Moreover, graphene is one of the best candidates to be used as transparent electrode for III-nitride semiconductor based optical devices, because of its marvelous transparency and electronic properties. In addition to the heterostructures, the intrinsic properties of III-nitride semiconductor itself are also important, especially for the unusual surface properties of InN. Accordantly, it is interesting to investigate the electronic properties and crystalline structure of these nitride semiconductors and its heterostructure with the proposed buffer layer of ScN and top electrode of graphene.
In Chapter 1, the basic properties of III-nitride semiconductors, rare-earth materials and graphene based optical and electronic devices will be introduced. Chapter 2 briefly describes the related experimental methods used in this study. Previous studies indicated when growing ScN on Si, a small amount of Sc silicides might form at the interface. Therefore, in Chapter 3.1, properties of Sc silicide overlayer on Si (111) substrate will be discussed, then the electronic and crystalline structures and the corresponding band line-up of ScN/GaN heterostructure will be presented in Chapter 3.2. Chapter 4 describes the layer number dependent optical and electronic properties of the device applications by using graphene as a transparent electrode on GaN surface. In Chapter 5, a fundamental study of in situ grown InN surface will be presented, in an attempt to understand the strong electron accumulation effect occurred in InN surface. Finally, Chapter 6 summarizes and pictures the future perspective of this study

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