Optical Absorbance of Porous Silicon on n-type Si (111) Surfaces Fabricated by Electrochemical Anodization Method

Porous silicon nanostructures (PSiN) are nanoporous materials which consist of uniform network of interconnected pore. The structure of PSiN is depending on etching parameters, including current density, HF electrolyte concentration, substrate doping type and level. In this work, the results of a structural p-type and n-type of porous silicon nanostructures were investigated by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) is reported. Samples were prepared by photo-electrochemical anodization of p- and n-type crystalline silicon in HF electrolyte at different etching time. The surface morphology of PSiN was studied by FESEM with same magnification shown n-type surface form crack faster than p-type of PSiN. While the topography and roughness of PSiN was characterize by AFM. From topography shown the different etching time for both type PSiN produce different porosity and roughness respectively. There is good agreement between p- and n-type have different in terms of surface characteristic.

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The Influence of Electrochemical Anodization for Porous Silicon Microcavity Fabrication

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.275-277.1960 ◽

2013 ◽

Vol 275-277 ◽

pp. 1960-1963

Author(s):

Hong Yan Zhang ◽

Xiao Yi Lv ◽

Zhen Hong Jia

Keyword(s):

Porous Silicon ◽

Stop Band ◽

Interface Layer ◽

Electrochemical Process ◽

Electrochemical Anodization ◽

Resonant Peak ◽

Chemical Dissolution ◽

Full Width ◽

Number Of Layers

The present work reports the electrochemical anodization for porous silicon microcavity (PSM) fabrication, including the number of layers and electrochemical process effect in the optical response quality of PSM. These PSMs have been obtained by using PS technology. It is found that the electrochemical process limits the maximum number of layers because there is a chemical dissolution effect during electrochemical anodization. The reflectance spectra of the PSMs indicates that stop-band and the resonant peak of the PSM shift down with the increases of the number of layers due to the decrease of layer's thickness. The value of the full width at half maximum (FWHM) dependents on the number of layers, and the number of layer increases when the FWHM decreases, which is due to the light scattering at roughness interface layer.

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Preparation of ZnF2 Nano-Particles by Electrochemical Anodization Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.476-478.1616 ◽

2012 ◽

Vol 476-478 ◽

pp. 1616-1620

Author(s):

Ye Zhang ◽

Hong Bing Ji

Keyword(s):

Crystalline Structure ◽

Applied Voltage ◽

Room Temperature ◽

Nano Particles ◽

Electrochemical Anodization ◽

Complex Solution ◽

Anodization Time ◽

Dominant Component ◽

Xrd Techniques ◽

Anodization Method

ZnF2 nano-particles were prepared by electrochemical anodization method at room temperature. Zn foil acted as anode and Pb sheet served as cathode, and the complex solution of NH4F-H2O2-C2H5OH was used as electrolyte. The morphology, composition and crystalline structure of the as-prepared product were characterized by SEM, EDS and XRD techniques. The results showed that the product was rhombic nano-particles with the length of 50-200nm and the width of 50-100nm, the crystalline structure of the product was ZnF2 and ZnO, and the ZnF2 was the dominant component. Effects of NH4F concentration, applied voltage and anodization time on the morphology of the product were investigated.

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Plasma Texturing and Porous Silicon Mirrors for Epitaxial Thin Film Crystalline Silicon Solar Cells

MRS Proceedings ◽

10.1557/proc-1101-kk04-01 ◽

2008 ◽

Vol 1101 ◽

Cited By ~ 1

Author(s):

Izabela Jozefa Kuzma-Filipek ◽

Filip Duerinckx ◽

Kris Van Nieuwenhuysen ◽

Guy Beaucarne ◽

Jef Poortmans

Keyword(s):

Thin Film ◽

Solar Cells ◽

Porous Silicon ◽

Crystalline Silicon ◽

Internal Reflection ◽

Electrochemical Anodization ◽

Silicon Solar Cells ◽

Textured Surface ◽

Epitaxial Silicon ◽

Substrate Interface

AbstractThin film silicon solar cells, consisting of an epitaxially grown active layer on a low quality highly doped silicon substrate, incorporate many attractive features usually associated with their sister cells based on bulk silicon. However, the efficiency of the current epitaxial semi-industrial screen printed cells is limited to 11-12% mainly due to optical shortcomings. This paper will give an overview of our work aimed at tackling the 2 most important problems: (i) Finding and implementing an adequate front surface texture and (ii) the simulation, fabrication and incorporation of an intermediate reflector.The former issue has been addressed by the development of plasma texturing based on halogen species. This method allows us to fulfil the sometimes contradictory requirements for the textured surface, i.e. a uniform and reduced reflection, a strong lambertian character to scatter the light and a limited removal of silicon. It will be shown that the scattering efficiency is dependent on both the wavelength of the impinging light and on the silicon removal during the texturing process.The second and main issue of this work is the limited absorption volume of the epitaxial layer. To resolve this drawback, an intermediate reflector is placed at the epi/substrate interface to enhance the path length of the low energy photons through the epi-layer. In practice, a multi-layer porous silicon stack is created by electrochemical anodization of the substrate. The reflection at the epi/reflector/substrate interface is a combination of several different effects including a Bragg mirror and Total Internal Reflection (TIR). Measurements of the external reflectance as well as extraction of the internal reflection parameters are used to clarify the issue. Advanced structures, including chirped porous silicon stacks, are introduced. Finally, the benefits of the reflector on the level of the epitaxial silicon solar cell are analysed. Efficiencies close to 14% are obtained for epitaxial cells incorporating an advanced porous Si reflector.

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