Investigation of selective junctions using a newly developed tunnel current model for solar cell applications

Varache, Renaud; Leendertz, Caspar; Gueunier‐Farret, Marie‐Estelle; Haschke, Jan; Muñoz, D.; Korte, Lars

doi:10.1016/j.solmat.2015.05.014

Cited by 251 publications

(154 citation statements)

References 27 publications

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“…The numerical device simulator AFORS-HET [27] was used to simulate the carrier extraction from a crystalline silicon absorber using different contact systems. The simulation model consisted of 250 µm thick n-type crystalline silicon symmetrically passivated by 5 nm intrinsic hydrogenated amorphous silicon.…”

Section: Other Measurements and Numerical Device Simulationmentioning

confidence: 99%

Oxygen vacancies in tungsten oxide and their influence on tungsten oxide/silicon heterojunction solar cells

Mews

Korte

Rech

2016

Solar Energy Materials and Solar Cells

142

105

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Tungsten oxide (WO x ) can be incorporated into amorphous/crystalline silicon heterojunction solar cells as hole contact and for interface modification between p-type amorphous silicon and indium tin oxide. This paper aims at understanding the influence of tungsten oxides properties on silicon heterojunction solar cells. Using in-system photoelectron spectroscopy on thermally evaporated WO x layers, it was verified that WO x with a stoichiometry close to WO 3 features a work function close to 6 eV and is therefore suitable as hole contact on silicon. Additionally the oxygen vacancy concentration in WO x was measured using photoelectron spectroscopy. High oxygen vacancy concentrations in WO x lead to a low band bending in the WO x /silicon-junction. Furthermore solar cells were fabricated using the same WO x , and the band bending in these cells is correlated with their fill factors (FF) and open circuit voltages (V OC ).Combining these results, the following picture arises: Positively charged oxygen vacancies raise the Fermi-level in WO x and reduce the band bending at the WO x /silicon-junction. This, in turn, leads to reduced V OC and FF. Thus, when incorporating WO x into silicon solar cells it is important to minimize the oxygen vacancy density in WO x . Therefore deposition methods, enabling adjustment of the WO x stoichiometry are preferable.

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Section: Other Measurements and Numerical Device Simulationmentioning

confidence: 99%

Oxygen vacancies in tungsten oxide and their influence on tungsten oxide/silicon heterojunction solar cells

Mews

Korte

Rech

2016

Solar Energy Materials and Solar Cells

142

105

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“…It allows one to calculate the capacitance and photoelectrical characteristics of the SC in the one-dimensional case. 32 Samples were also characterized from photoluminescence and X-ray diffraction measurements. The energy bandgap of the active layers determined by photoluminescence was found to be 1.03 eV.…”

Section: à3mentioning

confidence: 99%

Defect properties of InGaAsN layers grown as sub-monolayer digital alloys by molecular beam epitaxy

Baranov

Gudovskikh

Kudryashov

et al. 2018

Journal of Applied Physics

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The defect properties of InGaAsN dilute nitrides grown as sub-monolayer digital alloys (SDAs) by molecular beam epitaxy for photovoltaic application were studied by space charge capacitance spectroscopy. Alloys of i-InGaAsN (Eg = 1.03 eV) were lattice-matched grown on GaAs wafers as a superlattice of InAs/GaAsN with one monolayer of InAs (<0.5 nm) between wide GaAsN (7–12 nm) layers as active layers in single-junction solar cells. Low p-type background doping was demonstrated at room temperature in samples with InGaAsN layers 900 nm and 1200 nm thick (less 1 × 1015 cm−3). According to admittance spectroscopy and deep-level transient spectroscopy measurements, the SDA approach leads to defect-free growth up to a thickness of 900 nm. An increase in thickness to 1200 nm leads to the formation of non-radiative recombination centers with an activation energy of 0.5 eV (NT = 8.4 × 1014 cm−3) and a shallow defect level at 0.20 eV. The last one leads to the appearance of additional doping, but its concentration is low (NT = 5 × 1014 cm−3) so it does not affect the photoelectric properties. However, further increase in thickness to 1600 nm, leads to significant growth of its concentration to (3–5) × 1015 cm−3, while the concentration of deep levels becomes 1.3 × 1015 cm−3. Therefore, additional free charge carriers appearing due to ionization of the shallow level change the band diagram from p-i-n to p-n junction at room temperature. It leads to a drop of the external quantum efficiency due to the effect of pulling electric field decrease in the p-n junction and an increased number of non-radiative recombination centers that negatively impact lifetimes in InGaAsN.

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“…With AF ORS − HET [21], there is even a dedicated device simulation tool for this device type. However, its restrictions to 1D geometries limit its applicability to the structures with 3D features under investigation here.…”

Section: Macroscopic Device Characteristicsmentioning

confidence: 99%

Towards a Multi-scale Approach to the Simulation of Silicon Hetero-junction Solar Cells

Aeberhard¹,

Czaja²,

Ermes³

et al. 2016

JGE

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The silicon hetero-junction (SHJ) technology holds the current efficiency record of 25.6% for silicon-based single junction solar cells and shows great potential to become a future industrial standard for high-efficiency crystalline silicon (c-Si) cells. One of the main advantages of this concept over other wafer based silicon technologies are the very high open-circuit voltages that can be achieved thanks to the passivation of contacts by thin films of hydrogenated amorphous silicon (a-Si:H). The a-Si:H/c-Si interface, while central to the technology, is still not fully understood in terms of transport and recombination across this nanoscale region, especially concerning the role of the different localized tail and defect states in the a-Si:H and at the a-Si:H/c-Si interface and of the band offsets and band bending induced by the heterostructure potential and the large doping, respectively. For instance, a consistent microscopic picture of transport and recombination processes with treatment of thermal and tunneling mechanisms on equal footing is lacking. On the other hand, there are new SHJ device architectures like thin wafers with light trapping structures [1] or interdigitated back contact (IBC) cells [2], which define additional requirements for the modelling approach concerning the integration of 3D

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Investigation of selective junctions using a newly developed tunnel current model for solar cell applications

Cited by 251 publications

References 27 publications

Oxygen vacancies in tungsten oxide and their influence on tungsten oxide/silicon heterojunction solar cells

Oxygen vacancies in tungsten oxide and their influence on tungsten oxide/silicon heterojunction solar cells

Defect properties of InGaAsN layers grown as sub-monolayer digital alloys by molecular beam epitaxy

Towards a Multi-scale Approach to the Simulation of Silicon Hetero-junction Solar Cells

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