Structure Analysis of Oval Defect on Molecular Beam Epitaxial GaAs Layer by Cross-Sectional Transmission Electron Microscopy Observation

Kakibayashi, Hiroshi; Nagata, Fumio; Katayama, Yoshifumi; Shiraki, Y.

doi:10.1143/jjap.23.l846

Cited by 40 publications

(11 citation statements)

References 5 publications

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“…Stacking fault (SF) structures can grow from the substrate-epilayer interface during epitaxial growth [33,47]. In the present work, SFs form in a 10 µm GaAs layer grown by molecular beam epitaxy with room temperature electron density n ∼ 1.9 × 10 14 cm −3 and mobility ∼ 7400 cm 2 /Vs.…”

Section: S1 Stacking Fault Formationmentioning

confidence: 88%

“…Using a wavefunction size of approximately 10 nm, the critical density for exciton overlap in the 2D potential is 10 000 µm −2 . Therefore, the SF- Stacking fault (SF) structures can grow from the substrate-epilayer interface during epitaxial growth [33,47]. In the present work, SFs form in a 10 µm GaAs layer grown by molecular beam epitaxy with room temperature electron density n ∼ 1.9 × 10 14 cm −3 and mobility ∼ 7400 cm 2 /Vs.…”

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confidence: 86%

“…Strikingly, this inhomogeneity disappears when four SFs grow in an inverted pyramid structure consisting of four well-isolated {111} SF planes [ Fig. 1(b)], which we refer to as up, down, left and right [33]. The full width at half-maximum (FWHM) of the SF PL line in our sample is (77±19) µeV at zero magnetic field [21], somewhat narrower than excitonic lines associated with stacking faults in previous work [22,34].…”

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confidence: 99%

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Giant permanent dipole moment of two-dimensional excitons bound to a single stacking fault

et al. 2016

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We investigate the magneto-optical properties of excitons bound to single stacking faults in highpurity GaAs. We find that the two-dimensional stacking fault potential binds an exciton composed of an electron and a heavy-hole, and confirm a vanishing in-plane hole g-factor, consistent with the atomic-scale symmetry of the system. The unprecedented homogeneity of the stacking-fault potential leads to ultra-narrow photoluminescence emission lines (with full-width at half maximum 80 µeV) and reveals a large magnetic non-reciprocity effect that originates from the magnetoStark effect for mobile excitons. These measurements unambiguously determine the direction and magnitude of the giant electric dipole moment ( e · 10 nm) of the stacking-fault exciton, making stacking faults a promising new platform to study interacting excitonic gases.Introduction. The stacking fault (SF), a planar, atomically thin defect, is one of the most common extended defects in zinc-blende, wurtzite, and diamond semiconductors. A fundamental understanding of the SF potential is important for determining how the defect affects semiconductor device performance [1, 2], engineering heterostructures based on crystal phase [3][4][5], and providing a new twodimensional (2D) platform for fundamental physics [6,7]. Here we report on excitons bound to large-area, single SFs in high-purity GaAs, a unique system where SFs are easily isolated with far-field optical techniques. The atomic smoothness of the potential and extreme perfection of the surrounding semiconductor result in ultra-high optical homogeneity ( 80 µeV). This enables optical resolution of the SF exciton fine-structure and thus direct measurement of the giant built-in dipole moment ( e · 10 nm) via the magnetoStark effect. These results indicate that the extremelyhomogeneous SF potential may be promising for studies of many-body excitonic physics, including coherent phenomena [8-10], spin currents [11], superfluidity [12], long-range order [13][14][15][16][17], and large optical nonlinearities [18][19][20].Stacking fault photoluminescence. Figure 1(a) shows a spectrally resolved confocal scan of SF structures in a GaAs epilayer, excited with an above band-gap laser (1.65 eV, 1.5 K) [21]. The image is colored red, green or blue according to three characteristic emission bands shown in Fig. 1e. The narrow-band PL at 1.493 and 1.496 eV originates from excitons, electron-hole pairs, bound to the 2D SF potential [22,23]. The sample consists of a 10 µm GaAs layer on 100 nm AlAs on a 5 nm/5 nm AlAs/GaAs (10×) superlattice grown directly on a semi-insulating (100) GaAs substrate. Stacking fault structures nucleate near the substrateepilayer interface during epitaxial growth [21].The physical origin of the potential can be understood from the atomic structure of the SF defect: the lattice-plane ordering in the [111] direction of zinc-blende is modified

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Section: S1 Stacking Fault Formationmentioning

confidence: 88%

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confidence: 86%

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confidence: 99%

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Giant permanent dipole moment of two-dimensional excitons bound to a single stacking fault

et al. 2016

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“…Oval defects have been extensively studied in films grown by MBE, and are often associated with the Ga source due to spitting or oxide formation, but can also arise from substrate contamination or particulate transfer [34][35][36][37][38][39]. Oval defects have been previously reported in CSVT GaAs grown from single-crystal wafer sources and were attributed to surface contamination of the substrate prior to growth [29].…”

Section: Origin Of Surface Defectsmentioning

confidence: 99%

Analysis of performance-limiting defects in pn junction GaAs solar cells grown by water-mediated close-spaced vapor transport epitaxy

Boucher

Greenaway

Egelhofer

et al. 2017

Solar Energy Materials and Solar Cells

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Precursor and substrate costs currently limit the adoption of III-V photovoltaics for large scale manufacturing. Here, we use water-mediated close-spaced vapor transport (CSVT) to produce homojunction GaAs devices with pressed GaAs powder as an alternative to expensive gas-phase precursors. These unpassivated devices reach V oc > 910 mV, demonstrating the plausibility of CSVT as an alternative method for growth of III-V epitaxial films for photovoltaic devices. We find that Zn-doping of the absorber films decreases after a number of growths cycles using a single source, which suggests an alternative transport agent should be investigated for p-type doping. Performance of these solar cells is largely limited by formation of macroscopic surface defects which we find to be caused by particulate transfer from the source material and the formation of oxide phases during growth. We present strategies for mitigating these defects and improving device performance.

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“…[4] for details. The stacking fault defects nucleate at the substrate-epilayer interface during epitaxial growth [5], [6]. Two kinds of defects are observed, see Fig.…”

Section: A Sample Preparationmentioning

confidence: 99%

Optical visualization of radiative recombination at partial dislocations in GaAs

Karin

Linpeng

Ashish

et al. 2016

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)

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Abstract-Individual dislocations in an ultra-pure GaAs epilayer are investigated with spatially and spectrally resolved photoluminescence imaging at 5 K. We find that some dislocations act as strong non-radiative recombination centers, while others are efficient radiative recombination centers. We characterize luminescence bands in GaAs due to dislocations, stacking faults, and pairs of stacking faults. These results indicate that lowtemperature, spatially-resolved photoluminescence imaging can be a powerful tool for identifying luminescence bands of extended defects. This mapping could then be used to identify extended defects in other GaAs samples solely based on low-temperature photoluminescence spectra.

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Structure Analysis of Oval Defect on Molecular Beam Epitaxial GaAs Layer by Cross-Sectional Transmission Electron Microscopy Observation

Cited by 40 publications

References 5 publications

Giant permanent dipole moment of two-dimensional excitons bound to a single stacking fault

Giant permanent dipole moment of two-dimensional excitons bound to a single stacking fault

Analysis of performance-limiting defects in pn junction GaAs solar cells grown by water-mediated close-spaced vapor transport epitaxy

Optical visualization of radiative recombination at partial dislocations in GaAs

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