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Molecular beam epitaxy of germanium ...

Liu, Bing.

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Molecular beam epitaxy of germanium nanoclusters and indium gallium nitride thin films.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Molecular beam epitaxy of germanium nanoclusters and indium gallium nitride thin films./
作者:	Liu, Bing.
面頁冊數:	174 p.
附註:	Director: Stephen R. Leone.
Contained By:	Dissertation Abstracts International63-06B.
標題:	Physics, Condensed Matter. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3057784
ISBN:	0493732268

Molecular beam epitaxy of germanium nanoclusters and indium gallium nitride thin films.
Liu, Bing.

Molecular beam epitaxy of germanium nanoclusters and indium gallium nitride thin films. - 174 p.

Director: Stephen R. Leone.

Thesis (Ph.D.)--University of Colorado at Boulder, 2002.

Molecular beam epitaxy (MBE) is an important method of growth of thin crystalline films. In this thesis, I study MBE of Ge on Si(100) substrates and InGaN on silicon and sapphire substrates.

ISBN: 0493732268Subjects--Topical Terms:

1018743
Physics, Condensed Matter.

Molecular beam epitaxy of germanium nanoclusters and indium gallium nitride thin films.
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100 1 $a Liu, Bing. $3 1257045
245 1 0 $a Molecular beam epitaxy of germanium nanoclusters and indium gallium nitride thin films.
300 $a 174 p.
500 $a Director: Stephen R. Leone.
500 $a Source: Dissertation Abstracts International, Volume: 63-06, Section: B, page: 2881.
502 $a Thesis (Ph.D.)--University of Colorado at Boulder, 2002.
520 $a Molecular beam epitaxy (MBE) is an important method of growth of thin crystalline films. In this thesis, I study MBE of Ge on Si(100) substrates and InGaN on silicon and sapphire substrates.
520 $a Formation and evolution of three-dimensional Ge/Si(100) islands of diameters between 10 to 150 nm are first investigated. Three types of Ge clusters are identified <italic>ex situ</italic> by atomic force microscopy. These are (i) pyramidal islands with four {105} facets, (ii) dome-type islands with steeper facets of {113}, and (iii) very large and strain relaxed “superdome” islands of {112}, {125} and {215} facets. The island size, shape, and spatial distributions are examined as functions of major growth parameters such as substrate temperature, Ge beam flux, and time of annealing. The growth of Ge on Si(100) is divided into different regimes according to the total coverage. In the low and moderate coverage (10 monolayers) regime, formation of pyramidal islands is a kinetically favored process. These pyramids can evolve into larger dome type islands by several kinetic pathways including coarsening and coalescence. By appropriate low temperature annealing, an ensemble of pyramids can reach a local equilibrium state where the islands can have a narrow size distribution and a locally ordered spatial distribution. This can be useful for growth of self-assembled quantum dot devices. At higher coverages, very large superdome-type islands could form and grow at the expense of the nearby small pyramids and domes. However, the superdome island formation can also be suppressed by using high Ge beam fluxes. The mechanisms of the evolution of the Ge islands and the transition of one type of islands to another type of islands in each growth regime are discussed.
520 $a After I obtain an overall understanding of the growth and evolution of Ge nanoclusters on flat Si(100) surfaces, lateral alignment of Ge/Si(100) islands is explored using pre-patterned Si(100) substrates as the growth templates. The patterns are made by electron bean lithography and chlorine plasma etching. By minimizing the sizes of the patterns, laterally well-ordered arrays of Ge islands are achieved, and the mechanisms of the preferential nucleation of Ge islands at certain sites are examined.
520 $a Next, another important issue of preserving the two-dimensional growth of Ge on silicon by intentionally introducing some impurities (surfactants) during growth to suppress the three-dimensional Ge island formation is investigated. In particular, arsenic as a surfactant is studied. The role of arsenic in MBE of Ge on Si(100) is proposed to be both associated with reduction of Ge adatom surface diffusion and chemically decorating the surface atomic steps to increase the reactivity of the steps with the Ge adatoms.
520 $a Finally, I present studies of MBE of group III-nitride materials. The bulk strain of InGaN is first calculated using a simplified valence force field method. A phase diagram of InGaN is obtained for an overview of the thermodynamic properties of these materials. MBE experiments of GaN and InGaN thin films are then performed using both an electron cyclotron resonance (ECR) plasma and ammonia as the nitrogen sources. Thick GaN films of good crystal qualities and smooth surfaces are obtained by introducing a small amount of indium as a surfactant. In<sub>x</sub>Ga<sub>1−x</sub>N films with different indium fraction x are also achieved by balancing the major growth parameters such as the substrate temperature and In/Ga flux ratio. The mechanisms of the film growth and evolution are discussed.
590 $a School code: 0051.
650 4 $a Physics, Condensed Matter. $3 1018743
690 $a 0611
710 2 0 $a University of Colorado at Boulder. $3 1019435
773 0 $t Dissertation Abstracts International $g 63-06B.
790 $a 0051
790 1 0 $a Leone, Stephen R., $e advisor
791 $a Ph.D.
792 $a 2002
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3057784