Effect of As flux on InAs submonolayer quantum dot formation for infrared photodetectors

Alzeidan, Ahmad; Cantalice, T.F.; Vallejo, Kevin D.; Gajjela, Raja Sekhar Reddy; Hendriks, Arthur L.; Simmonds, Paul J.; Koenraad, P. M.; Quivy, A. A.

doi:10.1016/j.sna.2021.113357

Cited by 11 publications

(12 citation statements)

References 36 publications

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“…This partial WL formation, i.e., the first 1–2 BLs in both layers A1 and A2, is comparable to the formation of indium-rich clusters during the growth of submonolayer QDs where the QDs are formed by stacking ML high islands. 55 , 56 In the DE growth, the leftover indium on the growth surface from the droplet deposition reacts with the fresh As arriving on the surface forming such InAs-rich regions. In addition, the As–P surface exchange assists in the formation of a discontinuous layer of InAs(P).…”

Section: Resultsmentioning

confidence: 99%

Control of Morphology and Substrate Etching in InAs/InP Droplet Epitaxy Quantum Dots for Single and Entangled Photon Emitters

Gajjela

Sala

Heffernan

et al. 2022

ACS Appl. Nano Mater.

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We present a detailed atomic-resolution study of morphology and substrate etching mechanism in InAs/InP droplet epitaxy quantum dots (QDs) grown by metal–organic vapor phase epitaxy via cross-sectional scanning tunneling microscopy (X-STM). Two different etching processes are observed depending on the crystallization temperature: local drilling and long-range etching. In local drilling occurring at temperatures of ≤500 °C, the In droplet locally liquefies the InP underneath and the P atoms can easily diffuse out of the droplet to the edges. During crystallization, the As atoms diffuse into the droplet and crystallize at the solid–liquid interface, forming an InAs etch pit underneath the QD. In long-range etching, occurring at higher temperatures of >500 °C, the InP layer is destabilized and the In atoms from the surroundings migrate toward the droplet. The P atoms can easily escape from the surface into the vacuum, forming trenches around the QD. We show for the first time the formation of trenches and long-range etching in InAs/InP QDs with atomic resolution. Both etching processes can be suppressed by growing a thin layer of InGaAs prior to the droplet deposition. The QD composition is estimated by finite element modeling in combination with X-STM. The change in the morphology of QDs due to etching can strongly influence the fine structure splitting. Therefore, the current atomic-resolution study sheds light on the morphology and etching behavior as a function of crystallization temperature and provides a valuable insight into the formation of InAs/InP droplet epitaxy QDs which have potential applications in quantum information technologies.

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Section: Resultsmentioning

confidence: 99%

Control of Morphology and Substrate Etching in InAs/InP Droplet Epitaxy Quantum Dots for Single and Entangled Photon Emitters

Gajjela

Sala

Heffernan

et al. 2022

ACS Appl. Nano Mater.

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“…This distance (8 nm) is much smaller than the one usually found for double layers of InAs QDs (∼40-50 nm) [50]. It mainly results from the smaller size of the InAlAs QDs and their much lower In content which considerably weakens the local strain field [23]. The ideal seed layer is the one that can increase the density of InAs QDs in the top layer without interfering too much with their properties for a specific application [25,26].…”

Section: Resultsmentioning

confidence: 84%

“…The former does not increase their areal (2D) density but rather increases their bulk (3D) density, raising thus the elastic energy stored in the system. The latter can achieve a much higher surface density, supposedly in the low 10 12 cm −2 range, and provide an easy way to control their height, but the deposition is more complex, time consuming, and the growth conditions still need optimization [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Atomic-scale characterization of single and double layers of InAs and InAlAs Stranski-Krastanov quantum dots

Gajjela

Alzeidan

Curbelo

et al. 2022

Phys. Rev. Materials

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“…It is obvious that the SKWL with pure InAs relaxed higher (∼0.11 nm) than the discontinuous DEWL (∼0.08 nm) further supporting our observations on WL formation. The formation of a discontinuous WL might be analogous to the formation of In rich islands in InAs submonolayer QD growth [59,63], where the ML high In rich islands are formed and are stacked to form a QD [64]. In the DE case, there is an excess In on the surface after droplet formation as the surface is In terminated.…”

Section: De Versus Sk Wetting Layermentioning

confidence: 99%

Study of Size, Shape, and Etch pit formation in InAs/InP Droplet Epitaxy Quantum Dots

et al. 2022

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We investigated metal-organic vapor phase epitaxy grown droplet epitaxy (DE) and Stranski-Krastanov (SK) InAs/InP quantum dots (QDs) by cross-sectional scanning tunneling microscopy (X-STM). We present an atomic-scale comparison of structural characteristics of QDs grown by both growth methods proving that the DE yields uniform and shape symmetric QDs. Both DE and SKQDs are found to be truncated pyramid-shaped with a large and sharp top facet. We report the formation of localized etch pits for the ﬁrst time in InAs/InP DEQDs with atomic resolution. We discuss the droplet etching mechanism in detail to understand the formation of etch pits underneath the DEQDs. A summary of the eﬀect of etch pit size and position on ﬁne structure splitting (FSS) is provided via k .p theory. Finite element (FE) simulations are performed to ﬁt the experimental outward relaxation and lattice constant proﬁles of the cleaved QDs. The composition of QDs is estimated to be pure InAs obtained by combining both FE simulations and X-STM results. The preferential formation of {136} and {122} side facets was observed for the DEQDs. The formation of a DE wetting layer from As-P surface exchange is compared with the standard SKQDs wetting layer. The detailed structural characterization performed in this work provides valuable feedback for further growth optimization to obtain QDs with even lower FSS for optoelectronic applications and quantum technology.

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Effect of As flux on InAs submonolayer quantum dot formation for infrared photodetectors

Cited by 11 publications

References 36 publications

Control of Morphology and Substrate Etching in InAs/InP Droplet Epitaxy Quantum Dots for Single and Entangled Photon Emitters

Control of Morphology and Substrate Etching in InAs/InP Droplet Epitaxy Quantum Dots for Single and Entangled Photon Emitters

Atomic-scale characterization of single and double layers of InAs and InAlAs Stranski-Krastanov quantum dots

Study of Size, Shape, and Etch pit formation in InAs/InP Droplet Epitaxy Quantum Dots

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