Micro- and Nanotextured Silicon for Antireflective Coatings of Solar Cells

The paper deals with obtaining of textured silicon surfaces by chemical etching. As a result of experiments based on the modification and optimization of obtaining a textured silicon, several methods of chemical texturing of the crystalline silicon surface were developed. It was shown that modified isotropic and anisotropic etching methods are applicable to create a microrelief on the surface of silicon substrate. These methods in addition to their high conversion efficiency can be used for both mono- and multicrystalline silicon which would ensure their industrial use.

Download Full-text

Improving the Conversion Efficiency and Decreasing the Thickness of the HIT Solar Cell

MRS Proceedings ◽

10.1557/proc-1210-q07-01 ◽

2009 ◽

Vol 1210 ◽

Cited By ~ 2

Author(s):

Hirotada Inoue ◽

Yasufumi Tsunomura ◽

Daisuke Fujishima ◽

Ayumu Yano ◽

Shigeharu Taira ◽

...

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Conversion Efficiency ◽

Surface Passivation ◽

Crystalline Silicon ◽

Surface Recombination ◽

High Conversion ◽

Surface Recombination Velocity ◽

Substrate Thickness ◽

High Conversion Efficiency

AbstractIn order to reduce the power-generating cost of silicon solar cells, it is necessary to achieve a high conversion efficiency using a thinner crystalline silicon (c-Si) substrate. The HIT (Heterojunction with Intrinsic Thin-layer) solar cell is an amorphous silicon (a-Si) / c-Si heterojunction solar cell that exhibits the potential to make this possible. Our recent R&D activities have achieved the world’s highest conversion efficiency of 23.0% with a practical sized (100.4 cm2) HIT solar cell, by improving the quality of the surface passivation, reducing the optical absorption loss and reducing the resistance loss. We have also developed a HIT solar cell with a thickness of only 98 mm, which has a very high conversion efficiency of 22.8%. This value is comparable to that of the conventional HIT solar cell, which has a thickness of more than 200 mm. Moreover, we have fabricated HIT solar cells using thinner c-Si substrates (96 to 58 μm), and found that the Voc increased with decreases in the substrate thickness, and reached an extremely high value of 0.745 V with a thickness of only 58 μm. This indicates that the surface recombination velocity of the HIT structure is extremely low due to the excellent passivation of the c-Si surface.

Download Full-text

NOHSO4/HF – A Novel Etching System for Crystalline Silicon

Zeitschrift für Naturforschung B ◽

10.1515/znb-2007-1110 ◽

2007 ◽

Vol 62 (11) ◽

pp. 1411-1421 ◽

Cited By ~ 12

Author(s):

Sebastian Patzig ◽

Gerhard Roewer ◽

Edwin Kroke ◽

Ingo över

Keyword(s):

Gas Phase ◽

Chemical Etching ◽

Silicon Surface ◽

Crystalline Silicon ◽

Etching Solution ◽

Wide Range ◽

Ft Ir ◽

Wet Chemical ◽

Wet Chemical Etching ◽

Etching System

Solutions consisting of HF - NOHSO4 - H2SO4 exhibit a strong reactivity towards crystalline silicon which is controlled by the concentrations of the reactive species HF and NO+. Selective isotropic and anisotropic wet chemical etching with these solutions allows to generate a wide range of silicon surface morphology patterns. Traces of Ag+ ions stimulate the reactivity and lead to the formation of planarized (polished) silicon surfaces. Analyses of the silicon surface, the etching solution and the gas phase were performed with scanning electron microscopy (SEM), DR/FT-IR (diffusive reflection Fourier transform infra-red), FT-IR, Raman and NMR spectroscopy, respectively. It was found that the resulting silicon surface is hydrogen-terminated. The gas phase contains predominantly SiF4, NO and N2O. Furthermore, NH4+ is produced in solution. The study has confirmed the crucial role of nitrosyl ions for isotropic wet chemical etching processes. The novel etching system is proposed as an effective new way for selective surface texturing of multi- and monocrystalline silicon. A high etching bath service lifetime, besides a low contamination of the etching solution with reaction products, provides ecological and economical advantages for the semiconductor and solar industry.

Download Full-text