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Previous issue date: 2015-03-24 / Ternary alloys of III-V semiconductor materials, in particular Ga1-xInxSb, are ideal candidates for substrates because of the possibility to define the lattice constant as a function of concentration of the third element, indium, enabling the adjustment of the lattice parameter in accordance to the subsequent epitaxial layer. Therefore, the mono-crystallinity of the epitaxial layer is favored and the tensions at the interface layer/substrate are reduced, allowing to numerous possibilities and applications. Aluminum (Al) is considered an isoelectric dopant for Ga and In, meaning that it does not change the number of charge carriers, but increases the mobility in GaSb crystals. When Al is added to the Ga1-xInxSb ternary alloy, it can have influence over native defects passivating and/or compensating them. To understand the influence of Al on the distribution of indium (In) in ternary alloys of Ga1-xInxSb, pure and doped Ga0,8In0,2Sb crystals were obtained with approximately 1020 atoms/cm3 of Al using a vertical Bridgman system.Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), particle induced X-ray emission (PIXE) and particle induced gamma ray emission (PIGE) were used for the structural and compositional characterization of the crystals. The obtained crystals of Ga0,8In0,2Sb, doped with aluminum or not, exhibited segregation of the third element, however, for Ga0,8In0,2Sb:Al crystals the segregation decreased. The crystals of Ga0,8In0,2Sb:Al presented a good structural homogeneity when compared to the undoped alloy, and they were free from cracks and micro cracks. All of the obtained crystals presented precipitates, twins and grains with different concentrations of In. In the crystals doped with aluminum, single regions were observed in the solidification direction, which can be associated to a more uniform distribution of indium.The small compositional variation observed in the crystals, in radial direction, and measured by PIXE, may be related to the solid-liquid interface?s quasi-equilibrium behavior. The results indicated that aluminum has influenced the indium distribution in the crystals, in the solidification direction, and the electrical properties imply that the aluminum may have contributed to the generation of accepter defects such as GaSb, InSb e AlSb, wherein the number of charge carriers increased in the doped crystals. The possibility of complex defects generation such as (VGaGaSb), (VGaInSb) e (VGaAlSb) cannot be excluded, since the charge mobility in the doped crystals decreased. / Ligas tern?rias de materiais semicondutores III-V, nomeadamente Ga1-xInxSb, s?o candidatas ideais para substratos, pois a possiblidade de se definir a constante de rede em fun??o da concentra??o do terceiro elemento, o ?ndio, possibilita o ajuste do par?metro de rede de acordo com a camada epitaxial subsequente. Desta forma, a monocristalinidade da camada epitaxial ? favorecida e as tens?es na interface camada/substrato s?o diminu?das, introduzindo in?meras possibilidades e aplica??es. O alum?nio (Al) ? considerado um dopante isoel?trico do Ga e do In, isto ?, n?o altera o n?mero de portadores de carga, mas aumenta a mobilidade em lingotes de GaSb. Ao ser adicionando na liga tern?ria Ga1-xInxSb, pode influenciar passivando e/ou compensando os defeitos nativos. Para compreender a influ?ncia do Al na distribui??o do ?ndio (In) em ligas tern?ria de Ga1-xInxSb, foram obtidos lingotes de Gao,8In0,2Sb puros e dopados com aproximadamente 1020 ?tomos/cm3 de Al em um sistema Bridgman vertical.An?lises por microscopia eletr?nica de varredura (MEV), espectroscopia por dispers?o de energia (EDS), difra??o de raios X (XRD), emiss?o de raios X induzida por part?culas (PIXE) e emiss?o de raios gama induzida por part?culas (PIGE) foram utilizadas para a caracteriza??o estrutural e composicional dos lingotes. Os lingotes de Ga0,8In0,2Sb obtidos, dopados ou n?o com alum?nio, apresentaram segrega??o do terceiro elemento, por?m, para os lingotes Ga0,8In0,2Sb:Al a segrega??o foi menor. Os lingotes de Ga0,8In0,2Sb:Al apresentaram uma boa homogeneidade estrutural, livres de fissuras e micro trincas, quando comparados ? liga n?o dopada. Todos os lingotes obtidos apresentam forma??o de precipitados, maclas e gr?os com diferentes concentra??es de In. Nos lingotes dopados com alum?nio foram observadas regi?es com pequena quantidade de gr?os na dire??o da solidifica??o, que podem ser atribu?das a uma distribui??o do ?ndio mais uniforme. A pequena varia??o composicional observada nos lingotes, no sentido radial, mensurada por PIXE, pode ser atribu?da ao comportamento pr?ximo ao equil?brio da interface s?lido-liquido.Os resultados obtidos sugerem a influ?ncia do alum?nio na distribui??o de ?ndio nos lingotes, na dire??o da solidifica??o, ao mesmo tempo que as propriedades el?tricas sugerem que o alum?nio possa ter contribu?do para a gera??o de defeitos aceitadores como GaSb, InSb e AlSb, sendo que o n?mero de portadores de carga aumentou nos lingotes dopados. N?o se exclui a possibilidade da gera??o de defeitos complexos como (VGaGaSb), (VGaInSb) e (VGaAlSb), uma vez que a mobilidade das cargas nos lingotes dopados diminuiu.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/6092 |
| Date | 24 March 2015 |
| Creators | Streicher, Morgana |
| Contributors | Dedavid, Berenice Anina |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Engenharia e Tecnologia de Materiais, PUCRS, Brasil, Faculdade de Engenharia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | -7432719344215120122, 600, 600, 600, -655770572761439785, 4518971056484826825 |
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