Direct evidence of the Fermi-energy-dependent formation of Mn interstitials in modulation-doped Ga1−yAlyAs/Ga1−xMnxAs/Ga1−yAlyAs heterostructures

Yu, K. M.; Walukiewicz, W.; Wójtowicz, T.; Lim, W. L.; Liu, X.; Dobrowolska, M.; Furdyna, J. K.

doi:10.1063/1.1758291

Cited by 19 publications

(12 citation statements)

References 17 publications

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“…It turned out, however, that the presence of additional holes during the growth of (Ga,Mn)As layer increases the concentration of Mn interstitial donors (Mn I ) by the self-compensation mechanism. This diminishes net hole and Mn densities, so that T C gets actually reduced (Wojtowicz et al, 2003b;Yu et al, 2004). However, T C is increased if additional holes are transferred to (Ga,Mn)As layer after its epitaxy has been completed.…”

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confidence: 99%

Dilute ferromagnetic semiconductors: Physics and spintronic structures

2014

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This review compiles results of experimental and theoretical studies on thin films and quantum structures of semiconductors with randomly distributed Mn ions, which exhibit spintronic functionalities associated with collective ferromagnetic spin ordering. Properties of p-type Mncontaining III-V as well as II-VI, IV-VI, V 2 -VI 3 , I-II-V, and elemental group IV semiconductors are described paying particular attention to the most thoroughly investigated system (Ga,Mn)As that supports the hole-mediated ferromagnetic order up to 190 K for the net concentration of Mn spins below 10%. Multilayer structures showing efficient spin injection and spin-related magnetotransport properties as well as enabling magnetization manipulation by strain, light, electric fields, and spin currents are presented together with their impact on metal spintronics. The challenging interplay between magnetic and electronic properties in topologically trivial and nontrivial systems is described, emphasizing the entangled roles of disorder and correlation at the carrier localization boundary. Finally, the case of dilute magnetic insulators is considered, such as (Ga,Mn)N, where low temperature spin ordering is driven by short-ranged superexchange that is ferromagnetic for certain charge states of magnetic impurities.

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confidence: 99%

Dilute ferromagnetic semiconductors: Physics and spintronic structures

2014

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“…A possible explanation for this is based on observations of the behavior of Mn interstitials when annealed at low temperatures in (Ga,Mn)As. 20 The…”

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Structural and magnetic characteristics of MnAs nanoclusters embedded in Be-doped GaAs

2011

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We describe a systematic study of the synthesis, microstructure and magnetization of hybrid ferromagnet-semiconductor nanomaterials comprised of MnAs nanoclusters embedded in a p-doped GaAs matrix. These samples are created during the in situ annealing of Be-doped (Ga,Mn)As heterostructures grown by molecular beam epitaxy. Transmission electron microscopy and magnetometry studies reveal two distinct classes of nanoclustered samples whose structural and magnetic properties depend on the Mn content of the initial (Ga,Mn)As layer. For Mn content in the range 5% − 7.5%, annealing creates a superparamagnetic material with a uniform distribution of small clusters (diameter ∼ 6 nm) and with a low blocking temperature (T B ∼ 10 K). While transmission electron microscopy cannot definitively identify the composition and crystalline phase of these small clusters, our experimental data suggest that they may be comprised of either zinc-blende MnAs or Mn-rich regions of (Ga,Mn)As. At higher Mn content ( 8%), we find that annealing results in an inhomogeneous distribution of both small clusters as well as much larger NiAs-phase MnAs clusters (diameter ∼ 25 nm). These samples also exhibit supermagnetism, albeit with substantially larger magnetic moments and coercive fields, and blocking temperatures well above room temperature.

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“…Yu et al [10,12] reported that the concentration of Mn interstitials and Mn-related clusters increases with increasing Be concentration. Recently, it has been theoretically shown that the formation of Mn interstitials is enhanced with increasing the hole concentration due to the Fermi energy effect [11][12][13].…”

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confidence: 99%

“…When the growth of heavily Mn-doped GaAs layers is performed under high As pressure at low temperatures, point defects such as As-anti sites as well as interstitial Mn and As are inevitably formed in the crystal [9][10][11][12][13]. These point defects often act as a hole killer in Mn-doped GaAs.…”

Section: Introductionmentioning

confidence: 99%