Effect of Mn interstitials on the lattice parameter of Ga1−xMnxAs

Kuryliszyn‐Kudelska, I.; Domagała, J.; Wójtowicz, T.; Liu, X.; Łusakowska, E.; Dobrowolski, W.; Furdyna, J. K.

doi:10.1063/1.1634390

Cited by 46 publications

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“…3, we show the influence of annealing on the lattice parameter of the 700 Å thick Ga 0.94 Mn 0.06 As layer (s2). As reported before 13,22 , one effect of post-growth annealing is a reduction of the (Ga,Mn)As lattice parameter. This is interpreted as an effect of removing Mn I atoms from the (Ga,Mn)As volume.…”

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confidence: 85%

“…This is interpreted as an effect of removing Mn I atoms from the (Ga,Mn)As volume. Both experimental and theoretical studies 13,22,23 suggest that Mn interstitials are responsible for the observed lattice parameter increase in GaMnAs with Mn content, while substitutional Mn in Ga sites has only a small effect in this respect.The GaMnAs lattice parameter values calculated from angular positions of (004) Bragg diffraction peaks measured for as-grown as well as annealed pieces piece of s2 are given in Table 1. Thus, our results clearly indicate that Mn interstitials are removed from the (GaMn)As lattice by annealing under an As capping., in a similar way as by annealing in air or in nitrogen atmosphere, though on a shorter time scale than reported by Edmonds et.…”

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confidence: 99%

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Postgrowth annealing of (Ga,Mn) As under As capping: An alternative way to increase TC

Adell

Stanciu

Kanski

et al. 2005

Applied Physics Letters

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We demonstrate that in situ post-growth annealing of GaMnAs layers under As capping is adequate for achieving high Curie temperatures (T C ) in a similar way as ex situ annealing in air or in N 2 atmosphere practiced earlier. Thus, the first efforts give an increase of T C from 68 K to 145 K after 2 hours annealing at 180 °C. These data, in combination with lattice parameter determinations and photoemission results, show that the As capping acts as an efficient sink for diffusing Mn interstitials. In recent years, considerable progress has been done both in understanding the material properties, and improving the quality of low-temperature molecular beam epitaxy (LT MBE) grown GaMnAs films [2][3][4][5] . This has led to an increase of T c in GaMnAs from the previously "established" limit 6 of 110 K to 160 -170 K, as is now reported by several research groups 4,7,8 . The increase of T c by 50 -60 K was possible due to the identification and understanding of the role of structural defects, which compensate the Mn acceptors in GaMnAs. Since GaMnAs can only be grown by LT MBE, it hosts all the defects typical to LT GaAs 9-11 . At the MBE growth conditions suitable for GaMnAs deposition the prevailing structural defect is the As antisite (As Ga ). It is well known 10-12 that the maximum concentration of As Ga is close to 0.5%. Similar or even higher concentration of As Ga is expected in GaMnAs 13, 14 . In addition there is one defect specific to GaMnAs, namely Mn in interstitial positions (Mn I ). The importance of this defect was first analyzed theoretically 15 , and then Mn I was identified experimentally 16 . The negative impact of Mn I on the ferromagnetic properties of GaMnAs is due to two effects: Mn I acts as a double donor, and thus tends to compensate the p-doping In this letter we analyze the magnetic, structural and electronic properties of (Ga,Mn)As that is annealed under an As capping layer. Since the As capping protects the surface from 3 oxidation, the annealing can be carried out in air as well as in vacuum. We show that there is no essential difference in the annealing efficiency between the two environments. The behavior of the As cap during annealing in vacuum was monitored by reflection high energy electron diffraction (RHEED). The annealing temperature in vacuum was measured with an infrared pyrometer, and in air by means of a thermocouple in contact with the Mo-block holding the In-glued (Ga,Mn)As samples.We have grown a set of Ga 0.94 Mn 0.06 As layers with thicknesses in the range of 100 Å to 1000 Å, keeping the MBE growth procedure the same for all samples. Before sample growth, the Ga and Mn fluxes were carefully calibrated using RHEED intensity oscillations from a separate test sample. The GaMnAs samples were grown on semi-insulating GaAs(100) epiready substrates. Samples intended for photoemission were grown on n-type (Te doped) substrates. Each growth started with deposition of a 1000 Å thick high temperature (HT)GaAs buffer, and all samples were grown at the maximum substrate temperat...

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Postgrowth annealing of (Ga,Mn) As under As capping: An alternative way to increase TC

Adell

Stanciu

Kanski

et al. 2005

Applied Physics Letters

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“…(2) and (4); as-grown material with MnGa, Mnint, and AsGa (solid line), mixed crystal with all Mn int removed (dotted), material with the x i reduced to one third (dashed). ials [9][10][11] indicates that a large number of the compensating antisite defects (As Ga as well as some residual Mn int ) are present even in the best annealed samples with the minimum compensation.…”

Section: Discussionmentioning

confidence: 99%

Lattice Expansion of (Ga,Mn)As: The Role of Substitutional Mn and of the Compensating Defects

Mašek

Máca

2005

Acta Phys. Pol. A

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We apply the density-functional technique to determine the lattice constant of GaAs supercells containing Mn Ga , Mn int , and As Ga impurities, and use a linear interpolation to describe the dependence of the lattice constant a of Ga 1−x Mn x As on the concentrations of these impurities. The results of the supercell calculations confirm that Mn Ga does not contribute to the lattice expansion. The increase in a is due to both Mnint and As Ga , that are both created in the as-grown (Ga,Mn)As in proportion to x, and that are most probably present in a remarkable amount also in the best annealed materials.

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“…Problemas ocorrem quando, ao invés doíon Mn substituir umíon de Ga na rede, o Mn permanece em uma posição intersticial. Nesta configuração, ao invés de ser aceitador, oíon Mn passa a ser doador duplo, e além de não contribuir para o ferromagnetismo mediado por portadores (troca indireta), passa a acoplar antiferromagneticamente com os Mn substitucionais vizinhos [42]. Entrentanto, a técnica de post growth annealing permite remover grande parte dosíons Mn intersticiais, e desta forma, aumentar a qualidade das amostras.…”

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Propriedades eletrônicas de heteroestruturas semicondutoras magnéticas diluídas.

Marin¹

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O Universo nãoé apenas mais estranho do que imaginamos,é mais estranho do que podemos imaginar. Sir Arthur EddingtonSe um homem começar com certezas, ele terminará em dúvidas; mas, se ele se contentar em começar com dúvidas, ele talvez terminará com certezas. Sir Francis Bacon DON'T PANIC!The Hichthiker's Guide to the Galaxy Agradecimentos Agradeço a todos que, de uma forma ou de outra, me ajudaram a chegar até aqui:Ao ao meu orientador, Prof. Guilherme Sipahi, pela orientação, ajuda e amizade, dentro e fora do laboratório, em todos estes anos.A Prof. Sara Rodrigues, pelo apoio nos momentos de aperto e pela grande amizade.Ao Prof. Ivan da Cunha Lima, pelas discussões, pela ajuda e pela amizade, eà Derange, pela hospitalidade.Ao Prof. Gonzalo Travieso, pelas ajudas nas horas mais improváveis e pelos ensinamentos sempreúteis.Aos moradores de Asgard, passados e presentes (Hugo, Rodrigo, Léo, Dênis, Alexandre, Tiago, Magnus e Dorinha).Aos amigos da Física, alunos e funcionários e professores, que são tantos que não dá para agradecer a todos aqui.Aos amigos da turma, mesmo aqueles que não estão mais por perto.Aos amigos do Laboratório de Física Computacional (Weslley!, Keila, Aílton, Rodrigo, Luis, Suelene, Luciano, e claro, grande Marcel) pela ajuda em qualquer hora e pela paciência com os meus resmungos.Ao Gerson, Lucas, Matheus e Rafael Spa, pelas discussões intermináveis, argumentos implausíveis e amizade incondicional.A minha Bellinha, pela força, pela paciência (quase infinita) e pelo carinho (esse sim infinito).Aos meus pais, Gil e Léa, eà minha irmã, Marcela, que acreditaram em mim. Sem a ajuda de vocês não teria chegado onde estou. Soluções autoconsistentes da equação de massa efetiva são encontradas para oóxido semicondutor (Zn,Co)O. Será mostrada a separação de portadores por spin em função dos parâmetros variados, simulando diversas concentrações possíveis, utilizadas em sistemas descritos na literatura, e será analisado o comportamento dos perfis de potencial. Usando os dados obtidos, um diagrama de fases será traçado com base na polarização total ou parcial dos portadores, e o seu comportamento será discutido. Também serão mostradas as estruturas de bandas, os perfis de potencial e as distribuiçõe de carga do semicondutor (GaMn)As, variando as densidades de portadores e a direção do campo magnético intrínseco, gerado pela dopagem comíons magnéticos. SumárioOs resultados obtidos neste trabalho podem servir de guia para futuras experiências e para o desenvolvimento de dispositivos com semicondutores magnéticos diluídos baseados em (Zn,Co)O e (Ga,Mn)As. Os métodos aqui descritos são gerais e podem ser utilizados para outros materiais. 11 AbstractThis work presents a self-consistent multiband effective mass theory applied to diluted

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Effect of Mn interstitials on the lattice parameter of Ga1−xMnxAs

Cited by 46 publications

References 12 publications

Postgrowth annealing of (Ga,Mn) As under As capping: An alternative way to increase TC

Postgrowth annealing of (Ga,Mn) As under As capping: An alternative way to increase TC

Lattice Expansion of (Ga,Mn)As: The Role of Substitutional Mn and of the Compensating Defects

Propriedades eletrônicas de heteroestruturas semicondutoras magnéticas diluídas.

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