Effect of MW-ECR plasma hydrogenation on polysilicon films based solar cells

Madi, D.; Focsa, A.; Roques, S.; Schmitt, Sebastian W.; Slaoui, A.; Birouk, B.

doi:10.1016/j.egypro.2010.07.021

Cited by 7 publications

(3 citation statements)

References 23 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%

“…In this case, it is important to understand why rapid cooling steps result in lower V OC values compared to that obtained for slow cooling under hydrogen plasma. Assuming that improvement in open-circuit voltage is due to the passivation of defects by hydrogen diffused from the plasma but not to the defects structure change at the grain boundaries induced by temperature, the observed difference in V OC values in the temperature range 200-350°C can be either due to the formation of subsurface defects as platelets [14,15] or to the substantial etching of the n + emitter surface [10,15]. As explained [14,15], degradation of the surface and/or the generation of subsurface defects that result from the accumulation of diatomic hydrogen (H 2 ) located at a depth of 100 nm from the n + surface are harmful to the silicon based solar cells.…”

Section: Fig 1 Open-circuit Voltage Versus Hydrogenation Temperature ...mentioning

confidence: 99%

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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%

Section: Fig 1 Open-circuit Voltage Versus Hydrogenation Temperature ...mentioning

confidence: 99%

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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“…Relatively, it there have been various studies carried out on the hydrogenation of silicon [10,11]. For this material, the most efficient hydrogenation process boils down to brief thermal annealing of a layer of hydrogen-rich silicon nitride (SiN:H) having been deposited by PECVD on the crystalline silicon surface [12,13].The advantage of this process on others is the double function of SiN: H namely as an anti-reflective layer and passing on the surface of the emitters of the solar cells and it is more practical because it also adapts well to the formation stages of photovoltaic cells [14].…”

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

2014

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Effect of MW-ECR plasma hydrogenation on polysilicon films based solar cells

Cited by 7 publications

References 23 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

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

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