Carrier-selective contact GaP/Si solar cells grown by molecular beam epitaxy

Zhang, Chaomin; Vadiee, Ehsan; King, Richard R.; Honsberg, Christiana B.

doi:10.1557/jmr.2018.14

Cited by 14 publications

(6 citation statements)

References 29 publications

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“…However, any degree of terracing leads to high midgap DOS, similar to the abrupt unhydrogenated case. Overall, our results could explain the experimental results, which to date are giving relatively low open‐circuit voltages because of high recombination at the GaP/Si interfaces without either interdiffusion or an a‐Si interlayer . Further, the results show that the inclusion of hydrogen at the interface would be highly beneficial for realizing a low DOS at the interface, reducing recombination.…”

Section: Resultssupporting

confidence: 67%

“…Although there are a wide range of reported band offsets for the GaP/Si(001) heterojunction, our calculated band offset is consistent with the measured band offset reported by Sakata and Kawanami 54 and Roychowdhury et al 55 The calculated valence band offset is consistent with the fact that the GaP on Si layer may serve as a carrier selective contact. 59 In terms of this application, we believe that H atoms may tune the band offset of GaP/Si (001) heterojunction, by changing the charge distribution and passivating interface states.…”

Section: Resultsmentioning

confidence: 99%

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Electronic structure of GaP/Si(001) heterojunctions and the role of hydrogen passivation

Meidanshahi¹,

Zhang²,

Zou³

et al. 2019

Progress in Photovoltaics

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Epitaxially grown single crystal GaP on Si is of considerable interest due to being nearly lattice matched to Si, making it attractive for III‐V/Si solar cells. GaP has been used as a buffer layer for III‐V/Si solar cells and also in selective contact Si solar cells. The performance and functionality of such devices are strongly influenced by the presence of localized states at the GaP/Si interface. Here, we examine the electronic structure of GaP/Si(001) heterojunctions and the effect of hydrogen (H) passivation at the interface, in contrast to interface mixing, through density functional theory calculations. Our calculations show that due to the heterovalent mismatch nature of the GaP/Si interface, there is a high density of localized states at the abrupt GaP/Si interface due to the excess charge associated with heterovalent bonding, as reported elsewhere. We find that the addition of H leads to additional bonding at the interface, which mitigates the charge imbalance, and greatly reduces the density of localized states, leading to a nearly ideal heterojunction. A similar result is found with a completely intermixed interface (alternating cation and anion bonding) in terms of low interface state density. However, when the intermixing occurs through single‐layer or double‐layer terraces, the benefits of intermixing are lost and the interface state density reverts more to the abrupt interface case.

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Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Electronic structure of GaP/Si(001) heterojunctions and the role of hydrogen passivation

Meidanshahi¹,

Zhang²,

Zou³

et al. 2019

Progress in Photovoltaics

Self Cite

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“…Nevertheless, experimental demonstrations of GaP-contacted Si devices fall short of the promising simulations. [358][359][360][361][362][363] A crucial limitation of this approach is the classical use of MOCVD or molecular-beam epitaxy (MBE) to grow GaP, which is not standard for Si-cell processing. This can trigger bulk-silicon degradation which needs appropriate precautions.…”

Section: Other Metal Compoundsmentioning

confidence: 99%

“…GaP possesses several attractive properties suited to electron‐selective contacts in silicon solar cells: a small conduction‐band offset, demonstrated high n‐type doping and conductivity, and even a small lattice mismatch (with [100] silicon), which introduces the possibility of epitaxial growth. Nevertheless, experimental demonstrations of GaP‐contacted Si devices fall short of the promising simulations 358–363 . A crucial limitation of this approach is the classical use of MOCVD or molecular‐beam epitaxy (MBE) to grow GaP, which is not standard for Si‐cell processing.…”

Section: Other Metal Compoundsmentioning

confidence: 99%

Carrier‐selective contacts using metal compounds for crystalline silicon solar cells

Michel

Dréon

Boccard

et al. 2022

Progress in Photovoltaics

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Solar cells rely on the efficient generation of electrons and holes and the subsequent collection of these photoexcited charge carriers at spatially separated electrodes.High wafer quality is now commonplace for crystalline silicon (c-Si) based solar cells, meaning that the cell's efficiency potential is largely dictated by the effectiveness of its carrier-selective contacts. The majority of contacts currently employed in industrial production are based on highly doped-silicon, which can introduce negative side-effects including Auger recombination or parasitic absorption depending on whether the dopants are diffused into the absorber or whether they are incorporated into silicon layers deposited outside the absorber. Given the terawatt scale of deployment of c-Si solar cells, the search for alternative contacting schemes that can offer potential benefits in terms of performance, cost, ease of processing or stability is highly relevant. One such category of contacting schemes, with the potential to avoid the above mentioned issues, is that which employs metal compounds as the 'carrierselective' layer. The last 7 years has seen a surge in interest on this topic and a few promising families of materials have emerged, most prominently the alkali/alkalineearth metal compounds and the transition-metal oxides. The number of successful selective-contact demonstrations of materials within these families is fast increasing with the best solar cell demonstrations now exceeding 23%. However, in addition to improving their efficiency performance, several challenges remain if such contacts are to be considered for industrial adoption. These are mainly associated with poor stability, lack of compatibility with transparent electrodes and inability to be deposited using standard industrial techniques. This review covers the historical developments, current status and future prospects of metal-compound based selective contacts in the context of c-Si photovoltaics.

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“…ΔE HD-HA , ΔE LD-LA , ΔE LA-HD , and injection/collection barriers) which can be directly predicted from isolated structures (or medium size complexes) and are supposed to play a relevant role in the dynamics of charge carriers and excitons in OPVs. 166,[190][191][192][193][194][195][196] In addition, QM methods are generally used to describe/tune specific geometrical parameters, 197 stability and degradation processes, 198,199 predictions for ideal donor-acceptor pairs to improve OPV lifetimes and efficiencies, 200,201 chemical reactivity and electrical charges of force fields used in MM/MD simulations. 202,203 In MM and MD simulations, the interactions between molecules and atoms are described by a set of classic parameters, called force fields (commonly parameterized by QM-based calculations).…”

Section: Molecular Modelling Of D-a Interfaces and Interactionsmentioning

confidence: 99%

Review: materials and modelling for organic photovoltaic devices

Doat

Barboza

Batagin‐Neto

et al. 2021

Polymer International

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This review gives a simple and pedagogical introduction to the field of materials and their modelling for the active layer in organic photovoltaic devices. It gives a perspective on past work and a summary of the current state of the art. Given the extremely fast changes on-going in this field, it is hoped that this contribution will serve as both a timely snapshot and a pedagogical entry point to this fascinating subject. Furthermore, an example is given of how modelling can enhance the understanding of the structures and qualities of materials using a leading low-bandgap polymer donor and non-fullerene acceptor pair (PM6 and Y6).

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Carrier-selective contact GaP/Si solar cells grown by molecular beam epitaxy

Abstract: Abstract

Cited by 14 publications

References 29 publications

Electronic structure of GaP/Si(001) heterojunctions and the role of hydrogen passivation

Electronic structure of GaP/Si(001) heterojunctions and the role of hydrogen passivation

Carrier‐selective contacts using metal compounds for crystalline silicon solar cells

Review: materials and modelling for organic photovoltaic devices

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