PECVD SiN/sub x/ induced hydrogen passivation in string ribbon silicon [solar cells]

Yelundur, Vijay; Rohatgi, A.; Jeong, Ji-Weon; Gabor, Andrew M.; Hanoka, J. I.; Wallace, R.

doi:10.1109/pvsc.2000.915760

Cited by 7 publications

(16 citation statements)

References 7 publications

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“…As can be seen, for the scanning speeds of 1 mm s −1 , duration that temperature stays about 700 K or above is roughly about 1.6 s, which is considered as long enough to induce sufficient hydrogen passivation . Also, a cooling rate of 34 K s −1 , calculated from Figure (a), was observed at this condition, which is advantageous for the retention of hydrogen at the defect sites in silicon . As a result, a good degree of passivaton was confirmed by a 26% relative improvement of the effective lifetime, ( τ after annealing – τ before annealing ) τ before annealing ×100, at the injection level of 1 × 10 15 1 cm −3 .…”

Section: Resultsmentioning

confidence: 69%

“…Also, a cooling rate of 34 K s −1 , calculated from Figure (a), was observed at this condition, which is advantageous for the retention of hydrogen at the defect sites in silicon . As a result, a good degree of passivaton was confirmed by a 26% relative improvement of the effective lifetime, ( τ after annealing – τ before annealing ) τ before annealing ×100, at the injection level of 1 × 10 15 1 cm −3 . On the other hand, for the scanning speed of 15 mm s −1 , dwell time for maintaining the wafer temperature at 700 K or above significantly decreases, which may reduces the ability to retain hydrogen at defect sites in silicon.…”

Section: Resultsmentioning

confidence: 69%

“…A thin layer of silicon nitride (SiN x ), deposited on the silicon substrate as an anti‐reflection coating (ARC), is used as a source of hydrogen in the annealing process . In this process, hydrogen is diffused from the SiN x layer into the silicon substrate . The release of hydrogen occurs as temperature of the wafer exceeds the deposition temperature (T d ) of SiN x ; after that, the bonded hydrogen content in the SiN x film decreases with the increasing annealing temperatures .…”

Section: Introductionmentioning

confidence: 99%

“…In this process, hydrogen is diffused from the SiN x layer into the silicon substrate . The release of hydrogen occurs as temperature of the wafer exceeds the deposition temperature (T d ) of SiN x ; after that, the bonded hydrogen content in the SiN x film decreases with the increasing annealing temperatures . The level of hydrogen diffusion within the silicon wafer is then influenced by the annealing time during the annealing process …”

Section: Introductionmentioning

confidence: 99%

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Thermal Effects on the Hydrogen Passivation of Silicon Wafers During Diode Laser Annealing

Ahmmed

Song

Huda

2018

Physica Status Solidi (a)

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This paper presents a study of the laser induced thermal effects on the hydrogen passivation of silicon wafers. Thermal treatment, due to laser annealing, can be responsible for the release of atomic hydrogen from the dielectric layers, the diffusion of hydrogen into the silicon wafers and the passivation of defects. The whole process results in a reduction of active defects, and hence an increase of the minority carrier lifetime of the silicon wafers. Understanding of the mechanisms of heat transfer during the laser annealing is essential for obtaining an optimal hydrogenation effect. In this paper, a numerical model for evaluation of temporal and spatial temperature distributions in a silicon wafer during laser annealing is developed. The model is developed using the open‐source C + + framework known as OpenFOAM. A continuous wave (CW) diode laser of 808 nm wavelength is used for laser annealing of the silicon wafers containing dielectric layers of hydrogenated silicon nitride. The simulations are carried out at the experimental conditions and the impact of key laser annealing parameters, such as scanning speeds, laser power densities and substrates initial temperatures, are carefully investigated. The simulated results are then correlated with the experimental results of photoluminescene (PL) imaging and injection level dependent effective lifetime data. Our results show that the localized hydrogen passivation of the silicon wafers using laser annealing depends on the peak temperature and duration of heat. Additionally, it is found that the preheating of the wafer has a substantial effect on the reduction of thermal stress, while leading to a good degree of localized hydrogen passivation of the wafers. A correlation is also developed for the maximum spot temperature which will serve as a guideline for selecting optimum operating conditions.

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Section: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal Effects on the Hydrogen Passivation of Silicon Wafers During Diode Laser Annealing

Ahmmed

Song

Huda

2018

Physica Status Solidi (a)

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“…The effect of bulk passivation of crystal defects by atomic hydrogen has been studied extensively both on EFG and SR in several studies. [7][8][9][10] In our study we have chosen microwave-induced remote hydrogen plasma (MIRHP) passivation 11 which has proven to work excellently in passivating defects in ribbon silicon. 12,13 The passivation step was applied after the initial IV measurement; in this way the effect of hydrogenation can be quantified on cell parameter level.…”

Section: H Passivationmentioning

confidence: 99%

Record efficiencies for EFG and string ribbon solar cells

Hahn

Geiger

2003

Progress in Photovoltaics

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Solar cells have been processed on Edge-defined Film-fed Growth and String Ribbon silicon. Based on a standard process developed for different types of multicrystalline materials including evaporation of contacts and photolithography for front-contact formation, optimisations have been implemented to deal with the special needs of these low-cost ribbon materials. Especially a remote plasma hydrogenation step and a change from evaporated to screen-printed aluminium back-surface-field improved cell parameters drastically. Independently confirmed stable efficiencies of 16Á7% (EFG) and 17Á7% (String Ribbon) have been achieved on 4 cm 2 cells ( full area). These values represent the highest stable efficiencies obtained for multicrystalline silicon ribbons so far.

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New crystalline silicon ribbon materials for photovoltaics

Hahn

Schönecker

2004

J. Phys.: Condens. Matter

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The objective of this article is to review, in relation to photovoltaic applications, the current status of crystalline silicon ribbon technologies as an alternative to technologies based on wafers originating from ingots. Increased wafer demand, the foreseeable silicon feedstock shortage, and the need for a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of silicon, as wafers are crystallized directly from the melt at the desired thickness and no kerf losses occur. Therefore, they offer a high potential for significantly reducing photovoltaic electricity costs as compared to technology based on wafers cut from ingots. However, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. We will review the most successful of the ribbon techniques already used in large scale production or currently in the pilot demonstration phase, with special emphasis on the defects incorporated during crystal growth. Because of the inhomogeneous distribution of defects, mapped characterization techniques have to be applied. Al and P gettering studies give an insight into the complex interaction of defects in the multicrystalline materials as the gettering efficiency is influenced by the state of the chemical bonding of the metal atoms. The most important technique for improvement of carrier lifetimes is hydrogenation, whose kinetics are strongly influenced by oxygen and carbon concentrations present in the material. The best cell efficiencies for laboratory-type (17%-18%; cell area: 4 cm 2) as well as industrial-type (15%-16%; cell area: 80 cm 2) ribbon silicon solar cells are in the same range as for standard wafers cut from ingots. A substantial cost reduction therefore seems achievable, although the most promising techniques need to be improved.

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PECVD SiN/sub x/ induced hydrogen passivation in string ribbon silicon [solar cells]

Cited by 7 publications

References 7 publications

Thermal Effects on the Hydrogen Passivation of Silicon Wafers During Diode Laser Annealing

Thermal Effects on the Hydrogen Passivation of Silicon Wafers During Diode Laser Annealing

Record efficiencies for EFG and string ribbon solar cells

New crystalline silicon ribbon materials for photovoltaics

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