High quality amorphous–crystalline silicon heterostructure prepared by grid-biased remote radio-frequency plasma enhanced chemical vapor deposition

Mahtani, Pratish; Leong, Keith; Jovet, Bastien; Yeghikyan, Davit; Kherani, Nazir P.

doi:10.1016/j.jnoncrysol.2012.08.015

Cited by 11 publications

(6 citation statements)

References 47 publications

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“…While much research has been carried out to develop passivation technologies and correspondingly high-performance optoelectronic devices, there is limited reporting of theoretical and experimental studies that directly observe the relationship between photocarrier extraction and the strength of the near-surface electric field. Moreover, commonly reported passivation/extraction technologies assume a constant surface recombination velocity for all photocarriers approaching the surface ( 24 ). However, the optical generation profile within a given absorber varies with the wavelength of the incident light.…”

Section: Introductionmentioning

confidence: 99%

“…To minimize the effect of surface recombination, passivation technologies have been developed principally in two forms: chemical passivation and field passivation. Chemical passivation reduces the surface defect states by saturating the dangling bonds (20,21,(24)(25)(26)(27)(28). Field passivation, in contrast, creates a surface electric field via fixed charges within the adjoining dielectric films.…”

Section: Introductionmentioning

confidence: 99%

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Haynes-Shockley experiment analogs in surface and optoelectronics: Tunable surface electric field extracting nearly all photocarriers

2023

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Photocarriers predominantly recombine at semiconductor surfaces and interfaces, assuming high bulk carrier lifetime. Consequently, understanding the extraction of photocarriers via surfaces is critical to optoelectronics. Here, we propose Haynes-Shockley experiment analogs to investigate photocarrier surface extraction. A Schottky junction is used to tune the silicon near-surface electric field strength that varies over several orders of magnitude and simultaneously observe variations in broadband photocarrier extraction. Schottky barrier height and surface potential are both modulated. Work function tunable indium tin oxide (ITO) is developed to precisely regulate the barrier height and collect photocarriers at 0 V bias, thus avoiding the photocurrent gain effect. All experiments demonstrate >98% broadband internal quantum efficiency. The experiments are further extended to wave interference photonic crystals and random pyramids, paving a way to estimate the photogeneration rate of diverse surface light-trapping topologies by collecting nearly all photocarriers. The insights reported here provide a systematic experimental basis to investigate interfacial effects on photocarrier spatial generation and collection.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Haynes-Shockley experiment analogs in surface and optoelectronics: Tunable surface electric field extracting nearly all photocarriers

2023

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“…Our numerical results show that it is possible to obtain beyond 29% efficiency with 10 µm thick solar cell textured by slanted parabolic pores when the effective surface recombination velocities (SRVs) of the front and rear contacts approach 10 cm/s. Although such low values of SRV have been achieved experimentally for a planar Si wafer with low doping [26], it is challenging to achieve such low SRVs for c − Si with high emitter doping [27]. The 25% efficient PERL cell [25] has relatively lower emitter doping than that considered in [27] and consequently, lower front surface recombination velocities for electrons (S n ) and holes (S p ).…”

Section: Introductionmentioning

confidence: 99%

Designing High-Efficiency Thin Silicon Solar Cells Using Parabolic-Pore Photonic Crystals

Bhattacharya

John

2018

Phys. Rev. Applied

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We demonstrate the efficacy of wave-interference based light-trapping and carrier transport in parabolic-pore photonic crystal, thin-crystalline silicon (c − Si) solar cells to achieve above 29% power conversion efficiencies. Using rigorous solution of Maxwell's equations through a standard finite difference time domain (FDTD) scheme, we optimize the design of the vertical-parabolic-pore photonic crystal (PhC) on a 10 µm thick c − Si to obtain a maximum achievable photocurrent density (MAPD) of 40.6 mA/cm 2 , beyond the ray optics, Lambertian light-trapping limit. For a slanted-parabolic-pore PhC, that breaks x − y symmetry, improved light-trapping occurs due to better coupling into parallel-to-interface refraction (PIR) modes. We achieve optimum MAPD of 41.6 mA/cm 2 for a tilt angle of 10 • with respect to the vertical axis of the pores. This MAPD is further improved to 41.72 mA/cm 2 by introducing a 75 nm SiO2 anti-reflection coating (ARC) on the top of the solar cell. We use this MAPD and associated charge-carrier generation profile as input for numerical solution of the Poisson's equation coupled with semiconductor drift-diffusion equations using a Shockley-Read-Hall and Auger recombination model. Using experimentally achieved surface recombination velocities of 10 cm/s, we identify semiconductor doping profiles that yield power conversion efficiency over 29%. Practical considerations of additional upper-contact losses suggest efficiencies close to 28%. This improvement beyond the current world record is largely due to an open-circuit voltage approaching 0.8 V enabled by reduced bulk recombination in our thin-silicon architecture while maintaining a high short-circuit current through wave-interference-based lighttrapping.

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“…With silicon surface passivation processes, the surface recombination velocity will be significantly reduced and the effective minority carrier lifetime will be increased, which will enable c-Si solar cells with efficiency approaching and greater than 30%. [21][22][23][24][25]…”

Section: Introductionmentioning

confidence: 99%

Photonic crystals with a continuous, Gaussian-type surface profile for near-perfect light trapping

et al. 2018

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We show a unique design of teepee-like photonic crystal (TP-PC) structure that possesses a true gradient, Gaussian-type surface profile for smooth and accurate index matching between air and silicon for near-perfect light trapping. Such funnel-like, inverse-conical topography is capable of achieving near-zero optical reflection and near-unity solar absorption with excellent angular response over the entire visible light wavelength range. The fabrication only requires standard microelectronics reactive-ion etching (RIE) process. We demonstrate how various process parameters, such as RIE gas mixture ratio, RIE power, thickness of silicon dioxide (SiO 2 ) coatings, and lattice constant of the photonic crystal, can impact the details of the "Gaussian" profile and further improve the optical performance of the TP-PC structure at broad-λ, broad-θ, especially in the ultraviolet (UV) wavelength range. Our finite-difference time-domain (FDTD) simulation of the TP-PC structure reveals existence of multiple absorption resonances in the 800-to1100-nm wavelength range. Poynting vector plots show that such strong absorption enhancements at the resonant frequencies are due to long-lifetime photonic modes arising from parallel-to-interface refraction of the incoming sunlight and formation of vortex-like energy flow pattern inside the TP-PC structure. Our design will lead the way for future development of ultrathin, high-efficiency c-Si solar photovoltaics.

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High quality amorphous–crystalline silicon heterostructure prepared by grid-biased remote radio-frequency plasma enhanced chemical vapor deposition

Cited by 11 publications

References 47 publications

Haynes-Shockley experiment analogs in surface and optoelectronics: Tunable surface electric field extracting nearly all photocarriers

Haynes-Shockley experiment analogs in surface and optoelectronics: Tunable surface electric field extracting nearly all photocarriers

Designing High-Efficiency Thin Silicon Solar Cells Using Parabolic-Pore Photonic Crystals

Photonic crystals with a continuous, Gaussian-type surface profile for near-perfect light trapping

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