Reduction of surface defects in GaAs layers grown by MBE

Kawada, Hiroki; Shirayone, Shigeru; Takahashi, Ken

doi:10.1016/0022-0248(93)90384-9

Cited by 10 publications

(5 citation statements)

References 18 publications

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“…18, showing some defects which qualitatively resemble the ones discussed here. We observed defects with different shapes, with the most common being nearly round defects with a weak ridge in the center, as shown on Fig.…”

Section: Origin Of the Point-like Defectssupporting

confidence: 80%

“…According to Ref. 18 round defects with nucleus originate from Ga oxide or spitting, while obscure ovals arise from Ga droplets, oxides or particle contaminants. We attribute the observed defects to Ga nano-droplets emitted by the the Ga cell during growth.…”

Section: Origin Of the Point-like Defectsmentioning

confidence: 99%

“…PDs are better visible in the regions of lower density of crosshatches, however were observed in all regions, and for different MC samples which we investigated until now. They are not related to strain relaxation, but are generally attributed to particle contamination during growth or Ga source spitting 18 . These defects produce rather extended surface modulations, typically without lattice defects.…”

Section: Introductionmentioning

confidence: 99%

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Polariton states bound to defects in GaAs/AlAs planar microcavities

et al. 2012

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We report on polariton states bound to defects in planar GaAs/AlAs microcavities grown by molecular beam epitaxy. The defect types relevant for the spatial polariton dynamics in these structures are cross-hatch misfit dislocations, and point-like defects extended over several micrometers. We attribute the latter defects to Ga droplets emitted occasionally by the Ga cell during the growth. These defects, also known as oval defects, result in a dome-like local modulation of surface, which is translated into the cavity structure and leads to a lateral modulation of the cavity polariton energy of up to 15 meV. The resulting spatially localized potential landscape for the in-plane polariton motion creates a series of bound states. These states were characterized by spectrally resolved transmission imaging in real and reciprocal space, and reveal the spatial potential created by the defects. Interestingly, the defect states exhibit long lifetimes in the 10 ps range, which we attribute to a spatially smooth confinement potential.

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Section: Origin Of the Point-like Defectssupporting

confidence: 80%

Section: Origin Of the Point-like Defectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polariton states bound to defects in GaAs/AlAs planar microcavities

et al. 2012

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“…Another type of defect observed in this work were round defects having similar diameters and heights as oval defects. They were attributed 14 to Ga oxide or effusion cell spitting. We found that the defects investigated in our work originate from a GaAs thickness modulation, which we attribute to Ga droplets with sizes in the order of 100 nm emitted by the Ga source during growth.…”

Section: Point-like Defects In Gaas Heterostructuresmentioning

confidence: 99%

Structure and zero-dimensional polariton spectrum of natural defects in GaAs/AlAs microcavities

Zajac

Langbein

2012

Phys. Rev. B

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We present a correlative study of structural and optical properties of natural defects in planar semiconductor microcavities grown by molecular beam epitaxy, which are showing a localized polariton spectrum as reported in Zajac et al., Phys. Rev. B 85, 165309 (2012). The three-dimensional spatial structure of the defects was studied using combined focussed ion beam (FIB) and scanning electron microscopy (SEM). We find that the defects originate from a local increase of a GaAs layer thickness. Modulation heights of up to 140 nm for oval defects and 90 nm for round defects are found, while the lateral extension is about 2µm for oval and 4µm for round defects. The GaAs thickness increase is attributed to Ga droplets deposited during growth due to Ga cell spitting. Following the droplet deposition, the thickness modulation expands laterally while reducing its height, yielding oval to round mounds of the interfaces and the surface. With increasing growth temperature, the ellipticity of the mounds is decreasing and their size is increasing. This suggests that the expansion is related to the surface mobility of Ga, which with increasing temperature is increasing and reducing its anisotropy between the [110] and [110] crystallographic directions. Comprehensive data consisting of surface profiles of defects measured using differential interference contrast (DIC) microscopy, volume information obtained using FIB/SEM, and characterization of the resulting confined polariton spectrum are presented.

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“…15 Whist these do not contribute to crosshatch disorder, they do affect the potential landscape. These defects were eliminated in later samples by increasing the cell tip temperature and out-gassing.…”

mentioning

confidence: 99%

Design and characterization of high optical quality InGaAs/GaAs/AlGaAs-based polariton microcavities

Tinkler

Walker

Clarke

et al. 2015

Applied Physics Letters

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The presence of dislocations arising from strain relaxation strongly affects polaritons through their photonic component and ultimately limits experiments involving polariton propagation. In this work, we investigate the range of growth parameters to achieve high optical quality GaAs/AlxGa1−xAs-based microcavities containing strained InxGa1−xAs quantum wells and using differential interference contrast (Nomarski) microscopy deduce a design rule for homogeneous versus disordered structures. We illustrate the effect of disorder by contrasting observations of polariton condensates in relaxed and unrelaxed microcavities. In our optimized device, we generate a polariton condensate and deduce a lifetime for the interacting polariton fluid of 39 ± 2 ps.

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Reduction of surface defects in GaAs layers grown by MBE

Cited by 10 publications

References 18 publications

Polariton states bound to defects in GaAs/AlAs planar microcavities

Polariton states bound to defects in GaAs/AlAs planar microcavities

Structure and zero-dimensional polariton spectrum of natural defects in GaAs/AlAs microcavities

Design and characterization of high optical quality InGaAs/GaAs/AlGaAs-based polariton microcavities

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