Subpicosecond carrier trapping in high-defect-density amorphous Si and GaAs

Kühl, J.; Göbel, E. O.; Pfeiffer, Th.; Jonietz, A.

doi:10.1007/bf00614761

Cited by 60 publications

(14 citation statements)

References 21 publications

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“…The As concentration dependence was explained by the increase of the broadband absorption with As + implantation, leading to negative ∆n and thus negative ∆R, by Kramers-Kronig relation. Negative ∆R was observed earlier in amorphous GaAs [7] and Si [7,8] which was attributed to transitions involving midgap states. The sign change of ∆R in GaMnAs is somewhat similar to As + -ion implanted GaAs.…”

Section: Resultsmentioning

confidence: 89%

Time‐resolved differential reflection measurements on GaMnAs grown by molecular beam epitaxy

Kim

Lee

et al. 2005

phys. stat. sol. (c)

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We investigated time-resolved differential reflection in GaMnAs by pump-probe method at various wavelengths. The signals in GaMnAs were found to be more influenced by the compensating nature of the samples, rather than by the Mn concentrations. The time-resolved reflectivity of highly compensated samples exhibited stronger negative ∆R component at photon energies higher than the bandgap energy. This behaviour was similar to that of As + -ion implanted GaAs. Our results suggest that arsenic antisites (As Ga ) act as deep donors as in low-temperature grown GaAs and play an important role in compensating holes in GaMnAs.

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Section: Resultsmentioning

confidence: 89%

Time‐resolved differential reflection measurements on GaMnAs grown by molecular beam epitaxy

Kim

Lee

et al. 2005

phys. stat. sol. (c)

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“…In amorphous GaAs ͑Ref. 11͒ and Si, 11,12 negative ⌬R for E Ͼ E g was observed, which was attributed to the defect induced absorption associated with transitions involving midgap states. In crystalline LT GaAs, Gupta et al also observed initial negative ⌬R for E Ͼ E g .…”

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confidence: 94%

Effect of point defect and Mn concentration in time-resolved differential reflection in GaMnAs

Kim

Lee

et al. 2006

Applied Physics Letters

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Published by the AIP PublishingArticles you may be interested in Effect of low-temperature annealing on the electronic-and band-structures of (Ga,Mn)As epitaxial layers Quantitative analysis of the angle dependence of planar Hall effect observed in ferromagnetic GaMnAs film J. Appl. Phys. 105, 07C501 (2009); 10.1063/1.3055354Vanishing of ferromagnetic order in (Ga,Mn)As films at high hole concentrations: beyond the mean field Zener model

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“…1(b), the negative signal around zero delay in the results for the GaMnAs sample is due to FCA, which is enhanced with low-temperature growth due to the presence of defects. 41,42,47,52 The subsequent rise, which is characterized by a time constant of 1.8 ps, is attributed to the trapping of a portion of the electrons into As Ga defects, after which a positive signal is observed due to a DIA response associated with the trapped carriers.…”

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confidence: 98%

Observation of a blue shift in the optical response at the fundamental band gap in Ga1−xMnxAs

et al. 2012

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We report the observation of a sharp band-edge response in spectrally resolved differential reflectivity experiments on GaMnAs, in contrast to linear optical experiments in which large band-tail effects are known to dominate. The differential reflectivity response exhibits a blue shift relative to results in GaAs and LT-GaAs, consistent with the valence-band model of ferromagnetism. Our results demonstrate the utility of nonlinear optical techniques for studying the electronic structure of III-Mn-V diluted magnetic semiconductors.Diluted magnetic semiconductors (DMSs), which result from doping traditional semiconductors with magnetic impurities, have been the subject of an intensive research effort in recent years due to their potential for applications in spin-sensitive electronics, 1-3 photonics, 4-6 and opticallyaddressable nonvolatile memory. 7-9 This potential stems from the hole-mediated nature of the ferromagnetic coupling between the local magnetic impurities, which permits external control of magnetic characteristics using electrical gates or optical excitation. 10-13 GaMnAs has become the prototype DMS system, representing a model for understanding the nature of ferromagnetic coupling in the III-Mn-V DMS as well as for engineering the magnetic characteristics through tailored growth and processing. 14-16 A considerable body of research spanning the past decade has provided insight into the nature of exchange coupling between the Mn and hole spins, 17-21 the character of the magnetic anisotropy, 22-25 and the role of defects and compensation in determining the magnetic characteristics. 14,16,26,27 Despite these advances, unanswered questions remain with regard to the electronic structure and the appropriate model of ferromagnetic coupling. An active debate in the recent literature has focused on the position of the Fermi level, in particular whether the holes that mediate ferromagnetic coupling between the local Mn moments exist in the GaAs valence band or in a detached impurity band. 16,18,20,21,[27][28][29][30][31] As the physical mechanism of ferromagnetic coupling differs in the two limits, determining the correct picture is of central importance. Considerable input into the debate has been provided through recent experiments, with evidence supporting both points of view. [16][17][18][19][20][21]27,29 Nonlinear optical spectroscopy provides an alternative approach to investigating the position of the Fermi level in GaMnAs. In pump-probe spectroscopy, a femtosecond optical pulse (pump pulse) is used to excite electron-hole pairs in the semiconductor. These carriers modify the optical response of a subsequent, weaker pulse (probe pulse), providing a way to detect the presence of the pump-injected carriers. If the Fermi level in GaMnAs exists in the valence band, one expects to observe a blue shift in the band-edge optical response relative to undoped GaAs (the so-called Moss-Burstein shift) 32 since states that are full prior to the arrival of the pump pulse cannot lead to a signal. Alternatively, if t...

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Subpicosecond carrier trapping in high-defect-density amorphous Si and GaAs

Cited by 60 publications

References 21 publications

Time‐resolved differential reflection measurements on GaMnAs grown by molecular beam epitaxy

Time‐resolved differential reflection measurements on GaMnAs grown by molecular beam epitaxy

Effect of point defect and Mn concentration in time-resolved differential reflection in GaMnAs

Observation of a blue shift in the optical response at the fundamental band gap in Ga1−xMnxAs

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