Correlation of early-stage growth process conditions with dislocation evolution in MOCVD-based GaP/Si heteroepitaxy

Boyer, Jacob T.; Blumer, Ari N.; Blumer, Zak H.; Lepkowski, Daniel L.; Grassman, Tyler J.

doi:10.1016/j.jcrysgro.2021.126251

Cited by 10 publications

(7 citation statements)

References 64 publications

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“…The direct growth of high-quality III-V semiconductors on Si substrates for optoelectronic devices has been a key research goal for decades. Recently, advances in the control of crystalline defects in the epitaxial III-V layers − has enabled rapid performance increases for III-V-on-Si solar cells − and lasers. − V-groove Si, a type of selective area growth (a strategy used in many epitaxial systems − ) where a substrate uses selective etching of nanopatterns to produce {1 1 1}-faceted trenches on a (0 0 1)-oriented Si wafer, is one of the technologies that has enabled this progress. , The {1 1 1}-faceted surface of these templates stops the formation of antiphase domains (APDs), which historically have been a persistent problem for III-V-on-Si growth. V-grooves have been used for the direct growth of GaAs, − InP, − GaSb, and GaP − on Si for laser and solar cell applications via metalorganic vapor phase epitaxy (MOVPE).…”

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confidence: 99%

Coalescence of GaP on V-Groove Si Substrates

Saenz

Mangum

Schneble

et al. 2023

ACS Appl. Electron. Mater.

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Here, we study the morphology and dislocation dynamics of metalorganic vapor phase epitaxy (MOVPE)-grown GaP on a V-groove Si substrate. We show that Si from the substrate stabilizes the (0 0 1) GaP facet, which is critical for achieving coalescence. The SiN x caps covering the (0 0 1) tops of the V-grooves must be sufficiently small for the 3 × 1 GaP surface reconstruction caused by Si to continue to influence the GaP coalescence while the V-grooved sidewalls are covered. If the SiN x caps are too large, (1 1 1) diamond faceting develops in the GaP, and coalescence does not occur. On samples where coalescence is successful, we measure a root-mean-square roughness of 0.2 nm and a threading dislocation density of 5 × 10 7 cm −2 . Dislocation glide was found to begin during coalescence through transmission electron microscopy. With further TDD reduction, these GaP on V-groove templates will be suitable for III-V optoelectronic device growth.

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confidence: 99%

Coalescence of GaP on V-Groove Si Substrates

Saenz

Mangum

Schneble

et al. 2023

ACS Appl. Electron. Mater.

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“…Consequently, the degree of relaxation along that direction is R [110] = δ [110] /f × 100% from ECCI. 38 Figure 4(d) compares the HRXRD fitted strain relaxation with the ECCI-based MD density estimate. There is quantitative agreement within the error expected for both HRXRD and ECCI.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Log-Normal Glide and the Formation of Misfit Dislocation Networks in Heteroepitaxial ZnS on GaP

Fonseca Montenegro,

Baan,

Ghazisaeidi

et al. 2024

Crystal Growth & Design

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Scanning electron microscopy (SEM)-based electron channeling contrast imaging (ECCI) is used to observe and quantify misfit dislocation (MD) networks formed at the heteroepitaxial interface between ZnS and GaP grown by molecular beam epitaxy (MBE). Below a critical thickness of 15−20 nm, no MDs are observed. However, crystallographic features with strong dipole contrast, consistent with unexpanded dislocation half-loops, are observed prior to the formation of visible interfacial MD segments and any notable strain relaxation. At higher film thicknesses (20 to 50 nm), interfacial MD lengths increase anisotropically in the two orthogonal in-plane ⟨110⟩ line directions, threading dislocation (TD) density increases, and a roughening transition is observed from atomically smooth twodimensional (2D) to a multistepped three-dimensional (3D) morphology, providing evidence for step edge pinning via surface terminating dislocations. The ZnS strain relaxation, calculated from the total MD content observed via ECCI, matches the average strain relaxation measured by high-resolution X-ray diffraction (HRXRD). The MD lengths are found to follow a log-normal distribution, indicating that the combined MD nucleation and TD glide processes must have a normal distribution of activation energies. The estimated TD glide velocity (v g ) along [110] is almost twice that along [110], but in both directions shows a maximum as a function of film thickness, indicating an initial burst of plasticity followed by dislocation pinning.

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“…Other possible ways to reduce the dislocation density and cost of polished surfaces include use of nanopatterned substrates, and dislocation filtering approaches such as strained superlattices and thermal cycle annealing. [116][117][118] In contrast, mechanically stacked and wafer-bonded III-V/Si tandems push the efficiency of Si-based PV beyond 30%. Their few-μm thick III-V top cells are grown lattice-matched on GaAs parent wafers and transferred to independently fabricated Si bottom cells.…”

Section: Iii-v/si Tandem Junction Solar Cellsmentioning

confidence: 99%

Section: Iii-v Tandem Pvmentioning

confidence: 99%

Status report on emerging photovoltaics

Anctil,

Beattie,

Case

et al. 2023

J. Photon. Energy

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This report provides a snapshot of emerging photovoltaic (PV) technologies. It consists of concise contributions from experts in a wide range of fields including silicon, thin film, III-V, perovskite, organic, and dye-sensitized PVs. Strategies for exceeding the detailed balance limit and for light managing are presented, followed by a section detailing key applications and commercialization pathways. A section on sustainability then discusses the need for minimization of the environmental footprint in PV manufacturing and recycling. The report concludes with a perspective based on broad survey questions presented to the contributing authors regarding the needs and future evolution of PV.

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Correlation of early-stage growth process conditions with dislocation evolution in MOCVD-based GaP/Si heteroepitaxy

Cited by 10 publications

References 64 publications

Coalescence of GaP on V-Groove Si Substrates

Coalescence of GaP on V-Groove Si Substrates

Log-Normal Glide and the Formation of Misfit Dislocation Networks in Heteroepitaxial ZnS on GaP

Status report on emerging photovoltaics

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