Local-vibrational-mode spectroscopy of<i>DX</i>centers in Si-doped GaAs under hydrostatic pressure

Wolk, J. A.; Krüger, Michael; Heyman, James; Walukiewicz, W.; Jeanloz, Raymond; Haller, E. E.

doi:10.1103/physrevlett.66.774

Cited by 84 publications

(30 citation statements)

References 28 publications

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“…This problem is still under dispute [1]. In the alloy, the solution of this issue can be attempted without using highly sophisticated equipment needed for high pressure experiments [2].…”

mentioning

confidence: 99%

“…This problem is still under dispute [1]. In the alloy, the solution of this issue can be attempted without using highly sophisticated equipment needed for high pressure experiments [2].Our Alx Ga1-x As:Si samples were grown by the liquid phase electroepitaxy method [3] with two different alloy compositions: x = 0.25 (direct band-gap) and 0.43 (indirect band-gap). The doping levels and sample thicknesses were 1.5 x 10 18 cm-3, 360-400 μm and 5 x 10 17 cm-3 , 150 μm, respectively.…”

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confidence: 99%

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New Local Vibrational Modes Related to Silicon in Bulk AlGaAs

1995

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A silicon-related local vibrational mode absorption in AlGaAs is reported for the first time. It consists of six peaks grouped around 450 cm -1 which form a distinct pattern. We believe tlat the new local vibrational mode absorption is a fingerprint of a single defect. Among the discussed microscopic structures the most plausible is a SiG a -SiA S pair complex with Silks acceptor interacting with different Ga, Al nearest neighbour local environments.PACS numbers: 61.72. Vv, 63.20.Pw, 71.55.Eq A cucial factor limiting the sensitivity of local vibrational mode spectroscopy of ternary alloys is the sample thickness. With nonequilibrium growth techniques like MBE or MOCVD (metalorganic chemical vapour deposition) one is able to grow layers of up to 10 μm only. In this case a high doping density is required leading inevitably to creation of complexes and precipitates. Our LPEE (liquid phase electroepitaxy) grown thick (up to 400 μm) AlGaAs samples with very high compositional uniformity (±1%) and relatively low doping levels (5 x 10 17 cm-3) are a worldwide unique high quality material for studying local vibrational mode absorption of isolated defects and simple complexes in ternary compounds.In our experiment silicon, as a light impurity, has been introduced into the AlGaAs matrix. Although the Si impurity was thorouglly investigated in GaAs l ,. means of the LVM (local vibrational mode) technique (for review see e.g. [1]) there is little known about its behaviour in alloys. Additionally, Si is interesting from the point of view of its DX behaviour related to the localized vibrations. This problem is still under dispute [1]. In the alloy, the solution of this issue can be attempted without using highly sophisticated equipment needed for high pressure experiments [2].Our Alx Ga1-x As:Si samples were grown by the liquid phase electroepitaxy method [3] with two different alloy compositions: x = 0.25 (direct band-gap) and 0.43 (indirect band-gap). The doping levels and sample thicknesses were 1.5 x 10 18 cm-3, 360-400 μm and 5 x 10 17 cm-3 , 150 μm, respectively. The control (75i91

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“…This problem is still under dispute [1]. In the alloy, the solution of this issue can be attempted without using highly sophisticated equipment needed for high pressure experiments [2].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

New Local Vibrational Modes Related to Silicon in Bulk AlGaAs

1995

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“…These two facts of nature conspire against employing standard clamp diamond-anvil cells (DACs), in which it is extremely difficult to achieve pressure resolution and repeatability of less than a few kbar. Since clamp DACs are convenient for inserting into the restricted geometry of cryogenic FIR magnetooptical experiments, they have often been used for such studies in the past [2][3][4][5]. However, without in situ tuning, it becomes largely a matter of luck to detect the many fascinating resonant and anticrossing interactions that are possible in semiconductors.…”

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confidence: 99%

High-Pressure Studies of Semiconductors in the Far-Infrared: Donor States in Quasi-2D

et al. 2000

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We review recent experimental advances by the Buffalo group in performing far-infrared magnetospectroscopy under he tuning of applied high hydrostatic pressure. Experiments are reported for the effects of pressure on Si donors in modulation doped GaAs/AlGaAs quantum wells. We clearly observe pressure-mediated competition between free (i.e., Landau level) and bound electron states -the latter arising from both neutral (D 0 ) and charged (D -) donor species. With increasing pressure, there is a progression of the observed spectra from being dominated by cyclotron resonance and the D -singlet (or singlet-like bound magnetoplasmon) transitions, to showing the D0 is →2p+ line. The main reason for this evolution is the decrease in electrons due to the crossover of the Si levels associated with the F (well) and X (barrier) conduction minima. Indeed, for pressures above 30 kbar the Γ(well)-X(barrier) crossover quenches all the transitions. However, we find strong evidence that electrons are independently lost to a trap, which becomes active several kbar below this crossing. A possible candidate for this trap is residual Se impurities in the barriers. We present the results of detailed numerical calculation which are found to agree very well with the measured field dependencies of the cyclotron resonance, D0 and D -transition energies. In the sample with the highest doping, a new transition is observed for fields and pressures above 7.5 T and 5 kbar. Reasons for this apparent anomaly are discussed.

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“…LVM absorption spectroscopy is a direct method which can be used to determine the lattice sites of the Si-impurity in both the relaxed (deep DX -state) and unrelaxed (shallow hydrogenic state) states. Only one such absorption experiment has been carried out [6] on GaAs while it was subjected to a high hydrostatic pressure but there is still discussion about the interpretation of the results [1]. A clarification might ensue from studies of AlGaAs:Si for which the application of high pressure is not required for the formation of DX centres.…”

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“…If the vibrational mode of Si(DX) in GaAs were at 376 cm -1 (extrapolated frequency for zero pressure) [6], the line would not be observable for values of x > 0.22 because of the overlapping absorption from the "AlAs"-like reststrahl (see Fig. 1).…”

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Lattice Sites of Silicon Impurities in AlGaAs Grown by Liquid Phase Epitaxy

et al. 1996

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Localised vibrational mode infrared absorption (10 K) and Hall measurements were made on a series of Si doped Al xGa1-xAs samples with 0 < x < 0.25 grown by liquid phase epitaxy. Localised vibrational modes were detected from SiGa donors, Sim acceptors and SiGa-SiAs pairs which increased in frequency as x increased. The assignments of new lines observed at 386, 388 and 391 cm -1 are discussed in relation to possible perturbations of the lines from SiG a or SiAs. The presence of DX centres was inferred from observed persistent photoconductivity and attempts were made to relate this result to the presence of the new IR lines.

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Local-vibrational-mode spectroscopy ofDXcenters in Si-doped GaAs under hydrostatic pressure

Cited by 84 publications

References 28 publications

New Local Vibrational Modes Related to Silicon in Bulk AlGaAs

New Local Vibrational Modes Related to Silicon in Bulk AlGaAs

High-Pressure Studies of Semiconductors in the Far-Infrared: Donor States in Quasi-2D

Lattice Sites of Silicon Impurities in AlGaAs Grown by Liquid Phase Epitaxy

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