Surface Passivation Effect of Silicon Substrates due to Quinhydrone/Ethanol Treatment

Takato, Hidetaka; Sakata, Isao; Shimokawa, Ryuichi

doi:10.1143/jjap.40.l1003

Cited by 33 publications

(40 citation statements)

References 7 publications

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“…Typically values of S eff for iodine/ethanol passivated surfaces are in the 10-50 cm/s range [25]. Finally, typical values of about 10 cm/s were usually measured for quinhydrone/methanol passivated Si surfaces (the strategy used in this paper); being the lowest S eff reported 4.2 cm/s for a Fz Si wafer [20]. Accordingly, it cannot be assumed a constant S eff for all the samples, since it will be deeply modulated by the surface preparation and the wafer properties;…”

Section: Discussionmentioning

confidence: 75%

“…Before performing minority carrier lifetime measurements, wafer surfaces were passivated in order to reduce the surface recombination and enable an accurate bulk material minority carrier lifetime measurement. For wafers processed only under H 2 (no P diffusion and thus, no emitter), samples were dipped in HF and then passivated using a 0,05M quinhydrone-methanol solution as the passivating agent [20]. For samples treated under phosphine, surface layers were removed with an acidic etch consisting in a HNO 3 :H 2 O:HF solution (to eliminate the P-diffused layer) and then were passivated using the above mentioned wet method.…”

Section: Methodsmentioning

confidence: 99%

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Impact of metal-organic vapor phase epitaxy environment on silicon bulk lifetime for III–V-on-Si multijunction solar cells

García‐Tabarés

Rey‐Stolle

2014

Solar Energy Materials and Solar Cells

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With the final goal of integrating III-V materials on silicon substrates for tandem solar cells, the influence of the Metal-Organic Vapor Phase Epitaxy (MOVPE) environment on the minority carrier properties of silicon wafers has been evaluated. These properties will essentially determine the photovoltaic performance of the bottom cell in a III-V-on-Si tandem solar cell. A comparison of the base minority carrier lifetimes obtained for different thermal processes carried out in a MOVPE reactor on Czochralski silicon wafers has been carried out. An important degradation of minority carrier lifetime during the surface preparation (i.e. H 2 anneal) has been observed. Three different mechanisms have been proposed for explaining this behavior: 1) the introduction of extrinsic impurities coming from the reactor; 2) the activation of intrinsic lifetime killing impurities coming from the wafer itself; and finally, 3) the formation of crystal defects, which eventually become recombination centers. The effect of the emitter formation by phosphorus diffusion has also been evaluated. In this sense, it has been reported that lifetime can be recovered during the emitter formation either by the effect of the P on extracting impurities, or by the role of the atomic hydrogen on passivating the defects.Keywords: III-V on Silicon, minority carrier lifetime, MOVPE, heteroepitaxy, MJSC, bottom subcell.

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Section: Discussionmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 99%

Impact of metal-organic vapor phase epitaxy environment on silicon bulk lifetime for III–V-on-Si multijunction solar cells

García‐Tabarés

Rey‐Stolle

2014

Solar Energy Materials and Solar Cells

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“…In terms of passivation, it was shown that lifetime values measured after HQ-methanol treatment surpass those obtained with ethanol, or after iodine-methanol passivation. 38 The HQ-MeOH treatment also yields the strongest surface dipole, according to Kelvin probe measurements, even though the length of the methoxy moiety and of the resulting molecular layer is only 3-4 Å.…”

Section: Surface Dipolementioning

confidence: 94%

Ambient organic molecular passivation of Si yields near-ideal, Schottky-Mott limited, junctions

et al. 2012

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We report near-perfect transfer of the electrical properties of oxide-free Si surface, modified by a molecular monolayer, to the interface of a junction made with that modified Si surface. Such behavior is highly unusual for a covalent, narrow bandgap semiconductor, such as Si. Short, ambient atmosphere, room temperature treatment of oxide-free Si(100) in hydroquinone (HQ)/alkyl alcohol solutions, fully passivates the Si surface, while allowing controlled change of the resulting surface potential. The junctions formed, upon contacting such surfaces with Hg, a metal that does not chemically interact with Si, follow the Schottky-Mott model for metal-semiconductor junctions closer than ever for Si-based junctions. Two examples of such ideal behavior are demonstrated: a) Tuning the molecular surface dipole over 400 mV, with only negligible band bending, by changing the alkyl chain length. Because of the excellent passivation this yields junctions with Hg with barrier heights that follow the change in the Si effective electron affinity nearly ideally. b) HQ/ methanol passivation of Si is accompanied by a large surface dipole, which suffices, as interface dipole, to drive the Si into strong inversion as shown experimentally via its photovoltaic effect. With only ∼0.3 nm molecular interlayer between the metal and the Si, our results proves that it is passivation and prevention of metal-semiconductor interactions that allow ideal metal-semiconductor junction behavior, rather than an insulating transport barrier.

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“…In addition, at least 1 urn of Si surface material was stripped away for ensuring a clean surface. The etched sample was then passivated in a 0.05M quinhydrone-methanol solution bath [10]. As shown in Table I, the minority carrier lifetime suffers a reversible degradation-recovery process during the epitaxial growth process.…”

Section: Methodsmentioning

confidence: 99%

Evolution of the silicon bottom cell photovoltaic behavior during III–V on Si multi-junction solar cells production

García‐Tabarés

Grassman

Martín

et al. 2015

2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)

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-The evolution of the Si bulk minority carrier lifetime during the heteroepitaxial growth of III-V on Si multijunction solar cell structures via metal-organic vapor phase epitaxy has been analyzed. Initially, the emitter formation produces important lifetime degradation. Nevertheless, a progressive recovery was observed during the growth of the metamorphic GaAsP/Si structure. A step-wise mechanism has been proposed to explain the lifetime evolution observed during this process. The initial lifetime degradation is believed to be related to the formation of thermally-induced defects within the Si bulk. These defects are subsequently passivated by fastdiffusing atomic hydrogen -coming from precursor (i.e. PH 3 and AsH 3 ) pyrolysis-during the subsequent III-V growth. These results indicate that the MOVPE environment used to create the Ill-V/Si solar cell structures has a dynamic impact on the minority carrier lifetime. Consequently, designing processes that promote the recovery of the lifetime is a must to support the production of high-quality Ill-V/Si solar cells.Index Terms -Minority carrier lifetime, III-V on Si, MJSC, Si bottom cell.

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Surface Passivation Effect of Silicon Substrates due to Quinhydrone/Ethanol Treatment

Cited by 33 publications

References 7 publications

Impact of metal-organic vapor phase epitaxy environment on silicon bulk lifetime for III–V-on-Si multijunction solar cells

Impact of metal-organic vapor phase epitaxy environment on silicon bulk lifetime for III–V-on-Si multijunction solar cells

Ambient organic molecular passivation of Si yields near-ideal, Schottky-Mott limited, junctions

Evolution of the silicon bottom cell photovoltaic behavior during III–V on Si multi-junction solar cells production

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