Role of MW-ECR hydrogen plasma on dopant deactivation and open-circuit voltage in crystalline silicon solar cells

Madi, D.; Prathap, P.; Slaoui, A.

doi:10.1007/s00339-014-8665-z

Cited by 5 publications

(2 citation statements)

References 32 publications

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“…Despite plasma hydrogenation contributes to a large improvement in the electronic properties of thin n + pp + polycrystalline silicon cells, it simultaneously induces an etching of the emitter region (n + ) [9]. However, we showed in our previous works [10,11] that microwave plasma power around 650 W involving an electron cyclotron resonance (MW-ECR) induces an efficient passivation of defects with low damage of the emitter region (n + ). But a few works reported the direct effect of the n + emitter region on defects passivation in hydrogenated n + pp + cell structures and hydrogen diffusion in the polysilicon solar cell.…”

Section: Introductionmentioning

confidence: 90%

Defects passivation and H-diffusion controlled by emitter region in polysilicon solar cells submitted to hydrogen plasma

Mahdid,

Belfennache,

Madi

et al. 2023

JOR

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A significant cost reduction in photovoltaic cells could be achieved if they could be made from thin polycrystalline silicon (poly-Si) films. Despite hydrogenation treatments of poly-Si films are necessary to obtain high energy conversion, the role of the n+ emitter on defects passivation via hydrogen diffusion in n+pp+ polysilicon solar cells is not yet understood thoroughly. In this connection, influence of hydrogenation temperature and doping level of the n+ emitter on open-circuit voltage (VOC) were analyzed. It was found that VOC greatly improved by a factor of 2.9 and reached up to 430 mV at a microwave plasma power and hydrogenation temperature of 650 W and 400°C, respectively for a duration of 60 min. Moreover, slow cooling is more advantageous for high VOC compared to the rapid cooling. However, etching of the emitter region was observed, and this degradation is similar for both cooling methods. Furthermore, annealing of the hydrogenated cells in inert gas for 30 min revealed a slight increase in VOC, which reached 40-80 mV, depending on the annealing temperature. These results were explained by hydrogen atoms diffusing into the bulk of the material from subsurface defects that are generated during plasma hydrogenation process. Also, our findings show clearly that VOC values are much higher for a less doped phosphorus emitter compared to that of heavily doped. The origin of these behaviors was clarified in detail.

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Section: Introductionmentioning

confidence: 90%

Defects passivation and H-diffusion controlled by emitter region in polysilicon solar cells submitted to hydrogen plasma

Mahdid,

Belfennache,

Madi

et al. 2023

JOR

Self Cite

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“…In n + pp + polysilicon photovoltaic structures, exposing the region of the n + emitter to the flow of hydrogen is a well-accepted technique for the passivation of defects and various impurities existing within the material. However, the amount of hydrogen introduced into the p region is greatly reduced by the presence of the n + layer doped with phosphorus [15][16][17]. Additionally, the photovoltaic efficiency of an n + pp + cell made of polycrystalline silicon is much lower than that of monosilicon due to high defect concentrations, especially at the grain boundaries of the polycrystalline material.…”

Section: Introductionmentioning

confidence: 99%

Phosphorus deactivation mechanisms by hydrogenation in the n+ emitter region and its effect on defects passivation in n+pp+ poly-silicon solar cells

Ouldamer,

Belfennache,

Madi

et al. 2024

JOR

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Doping level of the n+ emitter region is an essential parameter that controls the performance of the n+ pp+ poly-silicon solar cells. Also, most poly-silicon n+ pp+ solar cell manufacturers apply hydrogenation from the phosphorus emitter n+ side to improve photovoltaic efficiency. Although hydrogen can passivate defects as well as it changes initial phosphorus doping level through phosphorus-hydrogen complex formation. Consequently, phosphorus deactivation can have a harmful effect on photovoltaic efficiency. In this context, the primary purpose of this work is to investigate the phosphorus deactivation in n+ emitter region and its effect on defects passivation of hydrogenated n+ pp+ poly-silicon solar cells. To do this, hydrogenation is performed by microwave plasma discharge involving an electron cyclotron resonance system. Besides, hydrogen passivates defects in poly-silicon, at the same time it deactivates phosphorus. For this reason, we have chosen to separate these simultaneous effects. So, we performed phosphorus deactivation on Schottky diodes-based mono-silicon, while defect passivation was operated in n+ pp+ poly-silicon solar cells. Our results reveal that hydrogen effectively deactivates phosphorus dopant. This effect is deeper in Schottky diodes with low initial phosphorus doping level where hydrogen diffuses easily in the bulk. This behavior is clearly revealed in open circuit-voltage values (Voc) measured on n+ pp+ samples. In fact, solar cells with low phosphorus concentration in n+ region revealed 319 mV compared to 230 mV for high doping level. Also, all n+ pp+ poly-silicon solar cells show a saturation of Voc at high microwave plasma power. Reasons for such case were explained and discussed in detail.

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A Discussion About Hydrogen Diffusion in n+pp+ Polysilicon Solar Cells Following Analysis of Both Dopant Deactivation and Defects Passivation

Madi

Belfennache

2021

Advances in Green Energies and Materials Technology

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Role of MW-ECR hydrogen plasma on dopant deactivation and open-circuit voltage in crystalline silicon solar cells

Cited by 5 publications

References 32 publications

Defects passivation and H-diffusion controlled by emitter region in polysilicon solar cells submitted to hydrogen plasma

Defects passivation and H-diffusion controlled by emitter region in polysilicon solar cells submitted to hydrogen plasma

Phosphorus deactivation mechanisms by hydrogenation in the n+ emitter region and its effect on defects passivation in n+pp+ poly-silicon solar cells

A Discussion About Hydrogen Diffusion in n+pp+ Polysilicon Solar Cells Following Analysis of Both Dopant Deactivation and Defects Passivation

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