Light and elevated temperature induced degradation in p-type and n-type cast-grown multicrystalline and mono-like silicon

Sio, Hang Cheong; Wang, Haitao; Wang, Quanzhi; Sun, Chang; Chen, Wei; Jin, Hao; Macdonald, Daniel

doi:10.1016/j.solmat.2018.03.002

Cited by 62 publications

(41 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The LeTID phenomenon has been observed on all different material types ranging from p-type multicrystalline silicon [1], Cz silicon [6], [7], cast-mono silicon [8], and even float-zone silicon [9], [10] to various n-type materials [8], [11]- [13]. All the materials have in common that in order to be susceptible to LeTID, a during the firing step (or hydrogen must be introduced otherwise [14,15]), and that the LeTID, and that the LeTID extent is highly sensitive to the peak firing temperature.…”

mentioning

confidence: 99%

“…The This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ LeTID kinetics appear to depend on the material type [8]- [10]. Whether this is a result of the difference in the crystalline structure, the difference in the present impurities, or whether this indicates a fundamental difference in the LeTID defect itself has not been clarified yet.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Temporary Recovery of the Defect Responsible for Light- and Elevated Temperature-Induced Degradation: Insights Into the Physical Mechanisms Behind LeTID

Kwapil

Schön

Niewelt

et al. 2020

IEEE J. Photovoltaics

View full text Add to dashboard Cite

The effect of light-and elevated temperature-induced degradation (LeTID) can be nonpermanently reversed by charge carrier injection below the degradation temperature (commonly used degradation temperatures are above ∼70°C). In this study, we show that the rate of temporary recovery depends strongly on the excess carrier density. We observe that the order of the reaction changes from pseudo-zero to first with increasing injection. The rate decreases slightly with increasing temperature. Since the samples can go through multiple degradation/recovery cycles without distinct changes in the degradation kinetics, the experimentally accessible recovered and degraded states are interpreted as manifestations of the equilibrium concentrations of the defect responsible for LeTID at different temperatures. Based on our observations, we argue that the process underlying LeTID degradation is the dissociation of a precursor rather than an association of two or more components. In light of the relation between LeTID susceptibility and bulk hydrogen concentration, we hypothesize that the LeTID precursor dissociates into the LeTID defect and monatomic hydrogen. Numerical simulations of the coupled rate equations including hydrogen interactions well reproduce the experimental observations; according to these results, the presence of a sink for the atomic hydrogen such as dopant atoms is paramount for the LeTID degradation. Index Terms-Degradation, Defect reactions, light-and elevated temperature-induced degradation (LeTID), model, silicon defects. I. INTRODUCTION A FTER the first description of the phenomenon later termed light-and elevated temperature-induced degradation (LeTID) [1], extensive research has been conducted on the influences determining the LeTID extent and kinetics. Noting the

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Temporary Recovery of the Defect Responsible for Light- and Elevated Temperature-Induced Degradation: Insights Into the Physical Mechanisms Behind LeTID

Kwapil

Schön

Niewelt

et al. 2020

IEEE J. Photovoltaics

View full text Add to dashboard Cite

show abstract

“…The differences seen between the maximum BOcorrected degradations indicates that LeTID formation starts to be observed after passing through a 640°C "barrier", illustrated in Figure 49(b). C. Chan et al [144] states that the LeTID is triggered if peak temperatures exceed approximately 700°C. This is because they found a considerably higher degradation in the sample fired at 700°C then in the sample fired at 675°C.…”

Section: A Methods Proposed For Letid and Bo-lid Separationmentioning

confidence: 99%

“…LeTID is commonly evaluated by the degradation behavior of the minority charge carrier lifetime in wafers [141], [142], [143], [144], [77], or the performance of cells [145], [140], [31], using illumination at an elevated temperature. Figure 24 shows the Kersten et al [31] data for mc-PERC cells degradation after illumination at 300W.…”

Section: Bo-lid and Letid In P-type Mc-simentioning

confidence: 99%

“…The temperature profiles measured using a thermocouple are shown in Figure 30. The cooling rate between the peak temperature and 400°C differ only slightly, with values close to 50°C/s for process #1, #5, and SBS, and close to 60°C/s for process #2, Prior to the degradation study all wafers were subjected to 200°C dark annealing (DA) for 20 minutes to obtain higher initial lifetimes [144]. The potential effect of this dark annealing on LeTID were considered negligible due to the short time [149].…”

Section: Source: Authormentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of impurities in the Brazilian solar grade silicon and LeTID investigations in p-type multi-Si

Knob¹

View full text Add to dashboard Cite

KNOB, D. Evaluation of impurities of the Brazilian solar grade silicon and LeTID investigations in p-type multi-Si. 2019. 119 p. Thesis (Doctorate in Nuclear Technology-Materials)-Instituto de Pesquisas Energéticas e Nucleares-IPEN-CNEN/SP. São Paulo The cost reductions and the environmental benefits aligned with global concerns about climate change have made solar photovoltaic technology the most installed source of energy in the power sector worldwide. Brazil has the largest know reserves of silicon in the world. Therefore, there is a huge potential for developing a national technology for purifying and manufacturing silicon wafers within an increasingly competitive and efficient photovoltaic industry. The IPEN initiative of investigating the production of metallic silicon and metallurgical route purification required a characterization of samples in different stages of production from quartz to wafer and understanding the characterization methods for silicon wafers taking into account the main defect mechanisms such as light-induced degradation. Metalic silicon is produced in IPEN via magnesiothermal reduction through acid leaching to form a metallurgical grade silicon with relatively low impurities. One more acid leaching step resulted in a specific ultrametallurgical grade silicon. The same acid leaching was processed in a commercially available Brazilian-made metallurgical grade silicon produced via carbothermal reduction. All samples impurities was measured by ICP-OES. The result is a material with ultra-metallurgical grade silicon content with excess of B and P. While wafer characterization was studied, an extensive investigation was taken on LeTID, which causes remain unknown, at Institute for Energy Technology, Norway. Neighboring high performance mc-Si p-type wafers were tested in different firing process conditions. The effects was investigated in terms of defects activation and a corresponding lifetime degradation and recovery at illuminated annealing. A sample with almost fully suppressed LeTID is shown. A new method have been proposed to separate Boron Oxygen-Light Induced Degradation effects of LeTID, enabling to measure even where it was thought to be fully suppressed. New models for LeTID defect formation and suppression are proposed. Both silicon purification and light-induced degradation characterization in mc-Si studies shows a wide range of research on new production routes that may require tailored processes of crystallization and solar cell manufacturing such as gettering and firing.

show abstract

Development of advanced hydrogenation processes for silicon solar cells via an improved understanding of the behaviour of hydrogen in silicon

Hallam

Hamer

Wenham

et al. 2020

Progress in Photovoltaics

View full text Add to dashboard Cite

The understanding and development of advanced hydrogenation processes for silicon solar cells are presented. Hydrogen passivation is incorporated into virtually all silicon solar cells, yet the properties of hydrogen in silicon are still poorly understood. This is largely due to the complex behaviour of hydrogen in silicon and its ability to exist in many different forms in the lattice. For commercial solar cells, hydrogen is introduced into the device through the deposition of hydrogen-containing dielectric layers and the subsequent metallisation firing process. This process can readily passivate structural defects such as grain boundaries but is ineffective at passivating numerous defects in silicon solar cells such as the boron-oxygen complex, responsible for light-induced degradation in p-type Czochralski silicon. This difficulty is due to the need to first form the boron-oxygen defect and also due to atomic hydrogen naturally occupying low-mobility and low-reactivity charge states. However, these challenges can be overcome using advanced hydrogenation processes incorporating excess carrier generation from illumination or current injection that increase the concentration of the highly mobile and reactive neutral charge state. As a result, after fast firing, additional low-temperature advanced hydrogenation processes incorporating illumination can be implemented to enable the passivation of difficult defects like the boron-oxygen complex. With the implementation of such processes for industrial silicon solar cells, efficiency improvements of 1.1% absolute can be obtained.

show abstract

Light and elevated temperature induced degradation in p-type and n-type cast-grown multicrystalline and mono-like silicon

Cited by 62 publications

References 54 publications

Temporary Recovery of the Defect Responsible for Light- and Elevated Temperature-Induced Degradation: Insights Into the Physical Mechanisms Behind LeTID

Temporary Recovery of the Defect Responsible for Light- and Elevated Temperature-Induced Degradation: Insights Into the Physical Mechanisms Behind LeTID

Evaluation of impurities in the Brazilian solar grade silicon and LeTID investigations in p-type multi-Si

Development of advanced hydrogenation processes for silicon solar cells via an improved understanding of the behaviour of hydrogen in silicon

Contact Info

Product

Resources

About