MBE growth and electroluminescence of ferromagnetic/non-magnetic semiconductor pn junctions based on (Ga,Mn)As

Ohno, Y.; Arata, Ikuo; Matsukura, F.; Ohtani, K.; Wang, S.; Ohno, Hideo

doi:10.1016/s0169-4332(00)00107-0

Cited by 23 publications

(17 citation statements)

References 5 publications

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“…Indeed, Wen et al (1968) 119 were perhaps the first to show that a ferromagnetic p-n junction, based on the ferromagnetic semiconductor CdCr 2 Se 4 doped with Ag acceptors and In donors, could act as a diode. Heavily doped p-GaMnAs/n-GaAs junctions were fabricated (Ohno, Arata, et al, 2000;Arata et al, 2001;Kohda et al, 2001;Johnston-Halperin et al, 2002;Van Dorpe, Liu, et al, 2003) to demonstrate tunneling interband spin injection. Incorporation of (Ga,Mn)As layer in the intrinsic region of p-i-n GaAs diode was shown to lead to an efficient photodiode, in which the Mn ions function as recombination centers (Teran et al, 2003).…”

Section: Spin Diodesmentioning

confidence: 99%

Spintronics: Fundamentals and applications

2004

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Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics. CONTENTS

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Section: Spin Diodesmentioning

confidence: 99%

Spintronics: Fundamentals and applications

2004

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“…Optical injection of spin-polarized carriers ͑both minority 4,5 and majority 4,6 ͒ has been known for some time. In addition, the relatively long spin diffusion lengths, 6,7 coherent spin transport across semiconductor interfaces, a successful fabrication of a magnetic/nonmagnetic p-n junction 8 based on the ͑Ga,Mn͒As material, 9 and the recent demonstration of a gatevoltage control of magnetization in ͑In,Mn͒As, 10 make semiconductors promising materials for spintronic applications. 2 In this paper we investigate the spin-charge transport in semiconductors under the conditions of inhomogeneous bipolar doping ͑there also exist theoretical proposals for semiconductor unipolar transistors and diodes 12 -a very different case from ours͒; we are not concerned with spin injection per se.…”

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confidence: 99%

Spin injection through the depletion layer: A theory of spin-polarizedp-njunctions and solar cells

2001

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A drift-diffusion model for spin-charge transport in spin-polarized p-n junctions is developed and solved numerically for a realistic set of material parameters based on GaAs. It is demonstrated that spin polarization can be injected through the depletion layer by both minority and majority carriers, making all semiconductor devices such as spin-polarized solar cells and bipolar transistors feasible. Spin-polarized p-n junctions allow for spin-polarized current generation, spin amplification, voltage control of spin polarization, and a significant extension of spin diffusion range. DOI: 10.1103/PhysRevB.64.121201 PACS number͑s͒: 72.25.Dc, 72.25.Fe, 85.75.Ϫd Spintronics 1,2 has played an important role in defining applications that are either not feasible or ineffective with traditional semiconductor electronics. Spintronic devices have found their niche in industries for magnetic read heads and nonvolatile memory cells. Here we propose and demonstrate a scheme for spintronics, a spin-polarized p-n junction, 2 which amplifies spin density, significantly extends the range of spin diffusion, electronically tailors spin polarization, and, in combination with light as a spin-polarized solar cell, generates spin-polarized currents with tunable spin polarization. We prove these concepts by solving drift-diffusion equations for a realistic device model based on GaAs, which demonstrates that spin polarization can be injected through the depletion layer. Possibility of injecting spin polarization through a transistor is also discussed.The electrical injection of spin-polarized carriers within all-semiconductor structures ͑from a magnetic into a nonmagnetic semiconductor͒ was recently realized experimentally 2 ͑the scheme proposed in Ref. 3͒. Optical injection of spin-polarized carriers ͑both minority 4,5 and majority 4,6 ͒ has been known for some time. In addition, the relatively long spin diffusion lengths, 6,7 coherent spin transport across semiconductor interfaces, a successful fabrication of a magnetic/nonmagnetic p-n junction 8 based on the ͑Ga,Mn͒As material, 9 and the recent demonstration of a gatevoltage control of magnetization in ͑In,Mn͒As, 10 make semiconductors promising materials for spintronic applications. 2 In this paper we investigate the spin-charge transport in semiconductors under the conditions of inhomogeneous bipolar doping ͑there also exist theoretical proposals for semiconductor unipolar transistors and diodes 12 -a very different case from ours͒; we are not concerned with spin injection per se. Our model device is a spin-polarized p-n junction with spin polarization induced ͑either optically-in which case we get a spin-polarized solar cell-or electronically͒ to minority or majority carriers. By studying spin-charge transport numerically across the depletion layer, we observe phenomena, all resulting from the fact that spin polarization is transferred ͑what we call injected͒ through the depletion layer.We introduce a drift-diffusion model for spin-charge transport in an inhomogeneously-doped s...

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“…This kind of diode structures has been fabricated of ferromagnetic Mn-doped p-type GaAs on top of n-type nonmagnetic GaAs. 17,29,30 Figure 9 shows schematically the effect of the band splitting on the energy-band diagram of a nondegenerate ferromagnetic pn junction. The dashed curves describe the spinpolarized bands on the ferromagnetic p side.…”

Section: A Diffusion Theorymentioning

confidence: 99%

“…Especially ͑Ga,Mn͒N is interesting, since the recent development in growth techniques for wurtzite III nitrides has resulted in successful fabrication of GaN-based optical and electrical devices. Some simple device structures such as pn junctions and light-emitting diodes, 17,29,30 GaMnAs/AlAs superlattices, 31 and ferromagnetic resonant tunneling diodes 19 have been made of III-V DMSs. Already decades ago experimental results for Schottky diodes based on ferromagnetic Eu chalgogenides have been presented.…”

Section: Introductionmentioning

confidence: 99%

Modeling of ferromagnetic semiconductor devices for spintronics

Лебедева

Kuivalainen

2003

Journal of Applied Physics

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We develop physical models for magnetic semiconductor devices, where a part of the device structure consists of a ferromagnetic semiconductor layer. First we calculate the effect of the exchange interaction between the charge carrier spins and the spins of the localized magnetic electrons on the electronic states, recombination processes, and charge transport in ferromagnetic semiconductors such as (Ga,Mn)As. Taking into account, e.g., the splitting of the conduction and valence bands due to the exchange interaction, we model the electrical characteristics of the basic magnetic semiconductor devices such as Schottky diodes consisting of a nonmagnetic metal/ferromagnetic semiconductor interface, pn diodes consisting of a ferromagnetic/nonmagnetic junction and bipolar transistors having a ferromagnetic emitter. The models predict that at temperatures close to the Curie temperature TC the electrical properties of the magnetic semiconductor devices become strongly dependent on the average spin polarization of the magnetic atoms. A feature in the models is that many device parameters such as diffusion lengths or potential barriers become spin dependent in magnetic semiconductor devices. In a ferromagnetic Schottky diode the sensitivity of the device current I to the external magnetic field may be as large as (∂I/∂B)I−1≈1/T at temperatures close to TC. In a ferromagnetic pn diode both the ideal and recombination currents become magnetic field dependent. In a ferromagnetic bipolar transistor the current gain shows the same sensitivity to the spin polarization as the dc current in the ferromagnetic pn diodes. According to our model calculations optimal structures showing the largest magnetization dependence of the electrical characteristics in III–V ferromagnetic semiconductor devices would be those where the magnetic side of the junction is of n type.

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MBE growth and electroluminescence of ferromagnetic/non-magnetic semiconductor pn junctions based on (Ga,Mn)As

Cited by 23 publications

References 5 publications

Spintronics: Fundamentals and applications

Spintronics: Fundamentals and applications

Spin injection through the depletion layer: A theory of spin-polarizedp-njunctions and solar cells

Modeling of ferromagnetic semiconductor devices for spintronics

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