Epitaxially grown emitters for thin film crystalline silicon solar cells

Nieuwenhuysen, Kris Van; Duerinckx, Filip; Kuzma, I.; Payo, María Recamán; Beaucarne, G.; Poortmans, Jef

doi:10.1016/j.tsf.2008.08.136

Cited by 20 publications

(10 citation statements)

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“…[6][7][8][9][10] Recently, PECVD epitaxial layers regained increased interest, however, as it was recognized that such layers are ideally suited to engineer silicon solar cells, either as (relatively thick) optically active absorber layers that replace the stillcostly wafer 11,12 or as thin layers for homojunction formation (electron or hole collectors, depending on the doping type). [13][14][15][16] Such thin epitaxial layers have also found application in certain high-efficiency heterojunction solar cell architectures and heterojunction field-effect transistors, illustrating that the same PECVD tools can be used to deposit various materials to engineer electronic devices. [17][18][19] Despite this, the precise influence of the plasma conditions on the electronic and microstructural quality of the grown layers has been elusive.…”

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confidence: 99%

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Demaurex¹,

Bartlomé²,

Seif³

et al. 2014

Journal of Applied Physics

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Low-temperature (≤200 °C) epitaxial growth yields precise thickness, doping, and thermal-budget control, which enables advanced-design semiconductor devices. In this paper, we use plasma-enhanced chemical vapor deposition to grow homo-epitaxial layers and study the different growth modes on crystalline silicon substrates. In particular, we determine the conditions leading to epitaxial growth in light of a model that depends only on the silane concentration in the plasma and the mean free path length of surface adatoms. For such growth, we show that the presence of a persistent defective interface layer between the crystalline silicon substrate and the epitaxial layer stems not only from the growth conditions but also from unintentional contamination of the reactor. Based on our findings, we determine the plasma conditions to grow high-quality bulk epitaxial films and propose a two-step growth process to obtain device-grade material.

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confidence: 99%

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Demaurex¹,

Bartlomé²,

Seif³

et al. 2014

Journal of Applied Physics

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“…Doped layers (p + or n + ) are necessary in crystalline silicon (c‐Si) solar cells to form the p–n junction or to keep the minority carriers away from recombination near the contacts. These doped layers or regions in silicon can be formed by a variety of techniques such as ion‐implantation , thermal diffusion from doped silicate layers deposited in a precursor environment (POCl 3 or BBr 3 diffusion) , growth of doped epitaxial layers , use of doped silicon nanoparticles , heat treatment of solid dopant source wafers (boron nitride) , or the diffusion of dopants from doped dielectric layers . The doped dielectric layers can be deposited at low temperatures (less than 250 °C) and then subjected to drive‐in at high temperature (∼1000 °C) to diffuse the dopants inside c‐Si bulk.…”

Section: Introductionmentioning

confidence: 99%

Analysis of p‐type SiO_x layers as a boron diffusion source for n‐type c‐Si substrates

Goyal

Urrejola

Hong

et al. 2016

Physica Status Solidi (a)

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We evaluate the use of p‐type silicon oxide (p‐SiOx) dielectric layers as a boron diffusion source for n‐type crystalline silicon (c‐Si) substrates. The p‐SiOx layers grown on n‐type c‐Si substrates by plasma enhanced chemical vapor deposition using a gas mixture of He/hexamethyldisiloxane/CO2/B2H6 are thermally stable and do not peel off during annealing up to 1050 °C, making them effective diffusion sources. The layers were examined before and after annealing with characterization techniques including spectroscopic ellipsometry and secondary ion mass spectrometry. We observe that there is a reduction in the thickness of the p‐SiOx layer after annealing by about 50%, and that boron diffuses into the n‐type c‐Si substrate, forming a p+ layer, limited by the formation of a carbon‐rich layer above the c‐Si surface. The concentration of holes in the diffused region was measured by the electrochemical capacitance–voltage technique, and it was found that essentially all the boron that diffused into the n‐type c‐Si was active, unaffected by the presence of carbon and oxygen atoms. The concentration of carriers can be controlled by the initial thickness of the p‐SiOx layers and the depth of the p+/n junction can be controlled by the time of annealing. A surface carrier concentration of 3 × 1019 at cm−3 and a sheet resistance of the order of 120 Ω sq−1 was obtained upon annealing at 1050 °C for 30 min.

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“…Efficiencies 12.3% [5] have also been confirmed from (30μm thin) epitaxial cells built on highly doped multi-crystalline Si substrates, by Chemical Vapor Deposition (CVD), with the front and back surfaces prepared by phosphorous diffusion. Efficiencies close to 15% have been achieved from cells with an emitter grown by CVD, creating thus a front surface field, onto a base epitaxialy grown [6] via optimization of the doping and thickness of epitaxial layer. Epitaxial solar cells with porous silicon brag reflector [7] and the large-area modules, based on integrated interconnected recrystallized silicon on ceramic cells [8], represent innovative concepts, which can fulfill the requirement of lowering the cost down to 45 €ct/W p [9].…”

Section: Introductionmentioning

confidence: 99%

Influence of recombination velocity and doping on the photovoltaic properties of epitaxial silicon solar cells

Perraki

2014

2014 IEEE International Energy Conference (ENERGYCON)

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This work evaluates the variations of photovoltaic properties of epitaxial silicon solar cells, fabricated on UMG-Si substrates, as a function of the epilayer thickness for different recombination velocities and doping concentrations. Device simulation and optimization software, developed in a previous paper, has been extended and adapted to n + pp + type epitaxial solar cells.The variations of photocurrent density J sc , and efficiency η, as a function of the epilayer thickness d, shows that solar cells, with BSF (low recombination velocities), are more effective than cells with ohmic contact (high recombination velocities) on their back surface. Regarding the effect of the doping concentration N A in the region p, J sc is not significantly influenced by this parameter , except for the cells with small grains fabricated on thin epilayer. In the rest of the cases J sc increases when the doping increases from 10 15 cm -3 to 10 17 cm -3 and the calculated solar cell efficiencies vary from 11% to 15% for cells with thin or thick epilayer respectively (independently of the grain size) while the optimum epilayer thickness shifts to lower values for cells with a thinner epilayer and small grains. The calculated results of maximizing η, show that the highest efficiencies correspond to cells fabricated on thick epilayers (d > 50μm which is lower compared to the experimental) and a doping N A =10 17 cm -3 independently of the grains size. When an epilayer thickness is lesser than this chosen, a minimal reduction in J sc and η is observed, but a significant gain in the material cost is achieved.The evaluation between the simulated curves of quantum efficiency QE, under 1000W/m 2 lighting, shows that, this is higher for the cells realized on thick epilayer. However, near the blue part of the solar spectrum, QE calculated is significantly higher for the cell with thin epilayer and small grains, compared to the ones with medium grains.

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Epitaxially grown emitters for thin film crystalline silicon solar cells

Cited by 20 publications

References 1 publication

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Analysis of p‐type SiO_x layers as a boron diffusion source for n‐type c‐Si substrates

Influence of recombination velocity and doping on the photovoltaic properties of epitaxial silicon solar cells

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Epitaxially grown emitters for thin film crystalline silicon solar cells

Cited by 20 publications

References 1 publication

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Analysis of p‐type SiOx layers as a boron diffusion source for n‐type c‐Si substrates

Influence of recombination velocity and doping on the photovoltaic properties of epitaxial silicon solar cells

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Analysis of p‐type SiO_x layers as a boron diffusion source for n‐type c‐Si substrates