Toward &gt;25% Efficient Monolithic Epitaxial GaAsP/Si Tandem Solar Cells

Grassman, Tyler J.; Derkacs, Daniel; Whipple, Steven; Stavrides, A.; Bremner, Stephen; Ringel, S. A.; Lepkowski, Daniel L.; Boyer, Jacob T.; Chmielewski, Daniel J.; Yi, Chuqi; Western, Ned J.; Mehrvarz, Hamid; Ho‐Baillie, Anita; Kerestes, Christopher

doi:10.1109/pvsc40753.2019.8980574

Cited by 17 publications

(11 citation statements)

References 16 publications

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“…Thin (50 nm) n- GaP/Si templates were grown on 4 in. Si(001) substrates offcut 2° toward [110] following our previously reported methods. , These wafers were then cleaved into quarters for regrowth of the different test structures, providing a nominally identical starting point for every case.…”

Section: Methodsmentioning

confidence: 99%

“…Recent years have witnessed multiple demonstrations of monolithic epitaxial III–V/Si solar cells, including GaAs 0.75 P 0.25 /Si dual-junction − and Ga 0.51 In 0.49 P/GaAs/Si triple-junction designs . Enabled by foundational work to mitigate the nucleation-related defects inherent to heterovalent GaP/Si integration, − a common integration pathway employed for these (and similar) PV-oriented heteroepitaxial III–V/Si systems is via metamorphic GaAs y P 1 y /GaP/Si compositional grading, typically in the form of step-graded buffers (SGBs).…”

Section: Introductionmentioning

confidence: 99%

“…The optically transparent (to photons transmitted by the upper junctions) SGB structure serves to controllably bridge the lattice mismatch between Si and the III–V upper junction composition(s). Nonetheless, while these early prototypes highlight the promise of this integrated materials system, the ultimate potential of the architecture is still yet to be fully realized due to, in large part, excessive threading dislocation (TD) content in the metamorphic III–V active layer(s). ,− …”

Section: Introductionmentioning

confidence: 99%

“…A significant amount of work has focused on the minimization of threading dislocation density (TDD) within the metamorphic GaAs y P 1– y /Si system. Careful optimization of the epitaxial growth has, for example, led to the demonstration of high-quality, p -type GaAs 0.75 P 0.25 /GaAs y P 1– y /Si with TDD as low as 4 × 10 6 cm –2 . , However, to yield the low-resistance band alignment at the III–V/Si interface needed to enable a series-connected, two-terminal tandem solar cell, ,,, it is generally recognized that an n- type interface is necessaryi.e., n- type III–V materials and an n- type Si surface (e.g., an n + -Si emitter layer). And yet, progress toward TDD reduction in the n -type polarity metamorphic structures significantly lags that of the p- type.…”

Section: Introductionmentioning

confidence: 99%

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Reduced Dislocation Introduction in III–V/Si Heterostructures with Glide-Enhancing Compressively Strained Superlattices

Boyer

Blumer

et al. 2020

Crystal Growth & Design

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The novel use of a GaAs y P1–y /GaP compressively strained superlattice (CSS) to provide enhanced control over misfit dislocation (MD) evolution and threading dislocation density (TDD) during GaP/Si metamorphic heteroepitaxy is demonstrated. Insertion of the CSS just after critical thickness, and thus prior to substantial dislocation introduction, is found to yield significantly reduced TDD in relaxed, 500 nm thick, n-type GaP/Si versus comparable control samples. The impact of CSS period count on average TDD and the overall dislocation network morphology was examined, supported by quantitative microstructural characterization, revealing a nearly 20× relative TDD reduction (to (2.4 ± 0.4) × 106 cm–2) with a 3-period CSS structure. A similarly low TDD ((3.0 ± 0.6) × 106 cm–2) is maintained when the resultant n-GaP/Si virtual substrate is used for the growth of a subsequent n-type GaAs0.75P0.25-terminal GaAs y P1–y step-graded metamorphic buffer. Although the physical mechanism for TDD reduction provided by these structures is not yet entirely understood, this initial work suggests that enhanced glide dynamics of MDs at or within the CSS placed early in the growth leads to a reduction in the total number of dislocations introduced overall, as opposed to annihilation-based reduction that occurs in conventional strained-layer superlattice dislocation filter approaches.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reduced Dislocation Introduction in III–V/Si Heterostructures with Glide-Enhancing Compressively Strained Superlattices

Boyer

Blumer

et al. 2020

Crystal Growth & Design

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“…7,8 As a transition layer between nonpolar Si substrates and polar III−V heterostructures, commonly a thin, pseudomorphic GaP buffer layer is deposited, 9 due to its lattice constant close to that of Si. On these GaP/Si(100) virtual substrates, lattice-mismatched absorber structures can be grown strain-free on top of a metamorphic buffer with a stepwise increase of As 10,11 or In, 12,13 or directly latticematched with the introduction of small amounts of N into GaP(As). 14,15 The industrially preferred deposition technique for III−V-based devices is metalorganic chemical vapor deposition (MOCVD), as it ensures well-defined epitaxy with a high purity on a large scale.…”

Section: Introductionmentioning

confidence: 99%

A Route to Obtaining Low-Defect III–V Epilayers on Si(100) Utilizing MOCVD

Nandy

Paszuk

Feifel

et al. 2021

Crystal Growth & Design

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Low-defect III−V multilayer structures grown on Si(100) open opportunities for a wide range of cost-effective high-performance photovoltaic and optoelectronic devices. For that, (Al)GaP epilayers prepared almost lattice-matched on Si(100) substrates can serve as high-quality virtual substrates for subsequent heteroepitaxial growth. The evolution of crystal defects, such as stacking fault pyramids or threading dislocations, needs to be impeded already during the first preparation step, the III−V-on-Si nucleation, as they tend to propagate into the subsequently grown layers and increase nonradiative electron−hole recombination rates, which finally degrade the device performance. We establish a ternary GaP/AlP pulsed nucleation process on Si(100) substrates fabricated by metalorganic chemical vapor deposition, and compare it to the defect evolution from pure GaP nucleation layers (NLs). The entire procedure was optically monitored in situ using reflection anisotropy spectroscopy. Crystal defects were investigated by electron channeling contrast imaging. GaP grown on GaP/ AlP NLs exhibits drastically reduced densities of threading dislocations and stacking faults by 1 and 2 orders of magnitude, respectively, compared to buffer layers grown on binary GaP NLs. We observed that the surface morphology at the initial stage of growth of these buffer layers is significantly smoother compared to the buffer layers grown on pure GaP NLs using atomic force microscopy. The proposed nucleation procedure here is supposed to substantially improve the crystalline quality of III−V buffer layers integrated on Si(100) wafers.

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Brief Outlook on Top Cell Absorber of Silicon‐Based Tandem Solar Cells

et al. 2023

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Silicon (Si) is a low‐cost, stable photovoltaic market contributor which is approaching its single‐junction theoretical efficiency limit. To further elevate the efficiency of crystalline Si (c‐Si) afterward, Si solar cells (SCs) need a proper top cell absorber in Si tandem SCs. Herein, the top cell absorber is studied by evaluating their current state of the art, the existing challenges, and possible future solutions which can enhance their efficiency. The progress of perovskite/Si tandem SC both for monolithic and four terminals is exceptional but still many challenges limit their commercialization. In view of these challenges, the relative's solutions are prescribed in detail to make possible their realization. III–V semiconductors being mature candidates still face a growth/fabrication problem, which makes them a costly option for III–V/Si tandem SCs. Effective growth strategies along with technical solutions are discussed in detail. Emerging chalcogenides are considered the future of tandem technology. Recent developments in the chalcogenides/Si tandem SC are highlighted and the possible options are presented. In the end, a short note is given on the near future tandem materials for Si tandem SCs.

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Toward >25% Efficient Monolithic Epitaxial GaAsP/Si Tandem Solar Cells

Cited by 17 publications

References 16 publications

Reduced Dislocation Introduction in III–V/Si Heterostructures with Glide-Enhancing Compressively Strained Superlattices

Reduced Dislocation Introduction in III–V/Si Heterostructures with Glide-Enhancing Compressively Strained Superlattices

A Route to Obtaining Low-Defect III–V Epilayers on Si(100) Utilizing MOCVD

Brief Outlook on Top Cell Absorber of Silicon‐Based Tandem Solar Cells

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