Ultralow Reflectivity and Light Trapping for Crystalline Si Solar Cells by Use of Surface Structure Chemical Transfer Method on Pyramidal Textured Surfaces

Journal of Electrical Engineering

et al. 2019

Black silicon layers were formed on silicon substrate by the surface structure chemical transfer method and by anodic etching method. Properties of microstructure of formed layers were experimentally studied by the electron microscopy methods (TEM) and characterized by statistical, Fourier and multifractal methods. Theoretical structures with defined fractal properties and surface roughness were generated and their microstructure properties were evaluated. Obtained results were used for the explanation of the real structure development during the forming procedure. By using of this approach, we study the correlation of roughness and fractality with optical properties. Black silicon layers were also investigated by using of Raman scattering method. Optimized theoretical model describing the 1st order of black Si Raman scattering profile was constructed and used for evaluation of the biaxial tensile stress introduced during etching procedure.

Section: Black Silicon and Theoretical Fractal Structuresmentioning

confidence: 99%

“…In the present study the nanocrystalline Si layers were formed by using the surface structure chemical transfer method (SSCT) [8][9][10][11]. In this procedure silicon surface is etched in solution of H 2 O 2 and HF.…”

Section: Papersmentioning

confidence: 99%

Black silicon – correlation between microstructure and Raman scattering

Jurečka

Pinčík

Journal of Electrical Engineering

et al. 2019

“…We have recently developed a fabrication method for ultralow reflectivity crystalline Si wafers which method simply includes contact of platinum (Pt) catalyst with Si wafers immersed in a hydrogen peroxide (H2O2) plus hydrofluoric acid (HF) solution called surface structure chemical transfer (SSCT) method [11][12][13][14]. In the present study, a nanocrystalline Si layer has been produced on a pyramidal Si surface by use of the SSCT Si surfaces, respectively, using a spin coating method, followed by heat treatment at 925 °C for 30 min in nitrogen.…”

Section: Introductionmentioning

confidence: 99%

Light trapping of crystalline Si solar cells by use of nanocrystalline Si layer plus pyramidal texture

Applied Surface Science

Nonaka

Onitsuka

et al. 2017

The surface structure chemical transfer (SSCT) method has been applied to fabrication of single crystalline Si solar cells with 170 μm thickness. The SSCT method, which simply involves immersion of Si wafers in H2O2 plus HF solutions and contact of Pt catalyst with Si taking only ~30 s for 6 inches wafers, can decrease the reflectivity to less than 3 % by the formation of a nanocrystalline Si layer. However, the reflectivity of the nanocrystalline Si layer/flat Si surface/rear Ag electrode structure in the wavelength region longer than 1000 nm is high because of insufficient absorption of incident light. The reflectivity in the long wavelength region is greatly decreased by the formation of the nanocrystalline Si layer on pyramidal textured Si surfaces due to an increase in the optical path length. Deposition of phosphosilicate glass (PSG) on the nanocrystalline Si layer for formation of pn-junction does not change the ultralow reflectivity because the surface region of the nanocrystalline Si layer possesses a refractive index of 1.4 which is nearly the same as that of PSG of 1.4∼1.5. The PSG layer is found to passivate the nanocrystalline Si layer, which is evident from an

“…Black− Si wafers have been produced using reactive ion etching [1][2][3][4], metal-assisted chemical etching [5][6][7][8][9][10], stain etching [11], electrochemical etching [11,12], vapor chemical etching [13], surface structure chemical transfer (SSCT) [14][15][16], etc. Reactive ion etching [1][2][3][4] requires an expensive apparatus, and throughput is considerably low, leading to high fabrication costs.…”

Section: Introductionmentioning

confidence: 99%

High conversion efficiency of crystalline Si solar cells using black − Si fabricated by SSCT method

Journal of Electrical Engineering

Onitsuka

Sakae

et al. 2017

We have developed a technology for fabrication of black − Si by use of the surface structure chemical transfer (SSCT) method. The ultralow reflectance below 3% results from formation of a graded porosity structure of a nanocrystalline Si layer formed by the SSCT method. The nanocrystalline Si layer with an extremely large surface area is effectively passivated by deposition of phosphosilicate glass (PSG) followed by heat treatment at 925 • C . After PSG passivation, the minority carrier lifetime greatly increases, and the internal quantum efficiency in the short wavelength region is also greatly increased. Using the SSCT method and the PSG passivation method, the high conversion efficiency of 19.7% is achieved.K e y w o r d s: surface structure chemical transfer, black Si, Si solar cells, surface passivation, reflectance, phosphosilicate glass