Energetics of Quantum Dot Formation and Relaxation of InGaAs on GaAs(001)

Pristovsek, Markus; Kremzow, Raimund; Kneissl, Michael

doi:10.7567/jjap.52.041201

Cited by 8 publications

(7 citation statements)

References 46 publications

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“…Both NWs show hexagonal cores composed of {110} facets and In x Ga 1– x As shells with a thickness of 8–12 nm, less than the nominal value of 18 nm (due to the formation of mounds on the sidewalls and possibly shadowing from neighboring NWs). We note that for In 0.6 Ga 0.4 As growth on planar GaAs(100) the critical thickness is ∼1 nm . Furthermore, in a study of similarly lattice mismatched Si/Ge core–shell NWs, Stranski–Krastanov growth with a wetting layer thickness of 1–2 nm was reported .…”

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confidence: 75%

“…We note that for In 0.6 Ga 0.4 As growth on planar GaAs(100) the critical thickness is ∼1 nm. 35 Furthermore, in a study of similarly lattice mismatched Si/Ge core−shell NWs, Stranski− Krastanov growth with a wetting layer thickness of 1−2 nm was reported. 23 For the NW on the left of Figure 3a, two faceted mounds are visible near the corners of the sidewall facets.…”

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confidence: 99%

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Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

et al. 2016

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Nanoscale substrates such as nanowires allow heterostructure design to venture well beyond the narrow lattice mismatch range restricting planar heterostructures, owing to misfit strain relaxing at the free surfaces and partitioning throughout the entire nanostructure. In this work, we uncover a novel strain relaxation process in GaAs/InGaAs core-shell nanowires that is a direct result of the nanofaceted nature of these nanostructures. Above a critical lattice mismatch, plastically relaxed mounds form at the edges of the nanowire sidewall facets. The relaxed mounds and a coherent shell grow simultaneously from the beginning of the deposition with higher lattice mismatches increasingly favoring incoherent mound growth. This is in stark contrast to Stranski-Krastanov growth, where above a critical thickness coherent layer growth no longer occurs. This study highlights how understanding strain relaxation in lattice mismatched nanofaceted heterostructures is essential for designing devices based on these nanostructures.

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confidence: 75%

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confidence: 99%

Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

et al. 2016

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“…A notable exception of the merely optical in situ approaches are the first MOVPE in situ STM images that were obtained at GaAs(100) surfaces at temperatures up to 650 °C and at atmospheric pressures . Even though the limited resolution is a drawback compared to STM at ambient or cryogenic temperatures, the in situ STM approach was also used to study quantum dot formation …”

Section: Epitaxial Reference Surfacesmentioning

confidence: 99%

“…Interesting in situ approaches include in situ photoluminescence (PL), which was demonstrated to predict the emission wavelength of InGaN QW‐based light emitting diodes (LEDs) already during growth . Ostwald ripening of InAs quantum dots on GaAs(100) could be observed with in situ STM, and a combined RAS/in situ STM study revealed the dependence of InGaAs quantum dot formation on different surface reconstructions . InGaAs quantum dot formation and island nucleation were studied also by in situ ellipsometry …”

Section: Epitaxial Reference Surfacesmentioning

confidence: 99%

In Situ Characterization of Interfaces Relevant for Efficient Photoinduced Reactions

Supplie

May

Brückner

et al. 2017

Adv Materials Inter

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which he pioneered and established. In general, interfaces do not only determine electronic properties of the final device; their atomic order also highly affects growth kinetics and defect formation. Moreover, the design of solid-liquid and hybrid interfaces determines their chemical reactivity and stability. In situ monitoring of interface preparation, formation, and interfacial reactions thus promises efficient process control. Paired with a detailed understanding of interface formation mechanisms, however, the true power of in situ control is to allow for specific modification and tuning of interface formation for the device of choice. There are several excellent reviews on in situ approaches covering wide ranges of materials from basic science to applications as well as varieties of preparation and analysis techniques. [2][3][4][5][6][7][8][9][10][11] As indicated in Figure 1, this review will be focused on in situ control over interfaces of materials that are relevant for photoinduced reactions in high-efficiency solar energy conversion and sensing applications with in situ control of semiconductor/polymer/ biological interfaces. We will restrict the techniques to realistic and complex, non-ultrahigh-vacuum (UHV) ambient, where in situ control is most demandingbut also highly desired. The more complex the interfacial reactions are, the more important is the in situ characterization. Ex situ approaches can contribute to an indirect understanding of interface formation, but to understand and, finally, control the dynamic processes taking place, real-time measurements are appropriate. The challenge, we are facing, is twofold: On the one hand, increased interaction with the surrounding ambient causes higher complexity. Yet at the same time, it decreases the number of applicable techniques. On the other hand, those techniques are often elaborate and not necessarily easy to interpret. In a nutshell, we will discuss four main topics:(i) Surface preparation during growth of structures for highefficiency solar energy conversion: World-record conversion efficiencies in both photovoltaics [12,13] and solar water splitting [14] are achieved with multijunction solar cells based on epitaxial III/V compound semiconductor structures. We will discuss in situ controlled preparation Solar energy conversion and photoinduced bioactive sensors are representing topical scientific fields, where interfaces play a decisive role for efficient applications. The key to specifically tune these interfaces is a precise knowledge of interfacial structures and their formation on the microscopic, preferably atomic scale. Gaining thorough insight into interfacial reactions, however, is particularly challenging in relevant complex chemical environment. This review introduces a spectrum of material systems with corresponding interfaces significant for efficient applications in energy conversion and sensor technologies. It highlights appropriate analysis techniques capable of monitoring critical physicochemical reactions in situ during non-vacuu...

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“…However, dislocation nucleation can occur within QDs especially during long InAs growth times. The associated plastic relaxation results in a rapid increase of island size since adding InAs to a more strain-relaxed island costs less strain energy 21 and the dislocated islands become more efficient at capturing monomers. In the present work we term such clusters “large 3D islands” (L3DI) 22 and they may also break the ISD-CZD connection.…”

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Spatial regularity of InAs-GaAs quantum dots: quantifying the dependence of lateral ordering on growth rate

Konishi

Clarke

Burrows

et al. 2017

Sci Rep

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The lateral ordering of arrays of self-assembled InAs-GaAs quantum dots (QDs) has been quantified as a function of growth rate, using the Hopkins-Skellam index (HSI). Coherent QD arrays have a spatial distribution which is neither random nor ordered, but intermediate. The lateral ordering improves as the growth rate is increased and can be explained by more spatially regular nucleation as the QD density increases. By contrast, large and irregular 3D islands are distributed randomly on the surface. This is consistent with a random selection of the mature QDs relaxing by dislocation nucleation at a later stage in the growth, independently of each QD’s surroundings. In addition we explore the statistical variability of the HSI as a function of the number N of spatial points analysed, and we recommend N > 103 to reliably distinguish random from ordered arrays.

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Energetics of Quantum Dot Formation and Relaxation of InGaAs on GaAs(001)

Cited by 8 publications

References 46 publications

Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

In Situ Characterization of Interfaces Relevant for Efficient Photoinduced Reactions

Spatial regularity of InAs-GaAs quantum dots: quantifying the dependence of lateral ordering on growth rate

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