Fabrication of Porous Silicon Microstructures using Electrochemical Etching (original) (raw)
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Porous silicon (PS) has been fabricated by Photo-electrochemical etching. Porous silicon was anodized on n-type Si in light using a current density of 20mA/cm2 for 10 min. The porous structure formation was confirmed using XRD and AFM studies. The root mean square (RMS) roughness of the Porous silicon layer is found to be around 47.5 nm and the ten point height was 317 nm. The average of pores diameter was 419.98nm, and the grain growth is columnar with a (211) preferred orientation. The grain size of the PS was estimated from the Scherer’s formula and found to be 73 nm. All the properties of the porous silicon layer, such as porosity and the thickness depend on the anodization parameters. The porosity (P) was approximately 77 %. The thickness of the layer formed during an anodization in constant current was 3.54nm in gravimetric method, while its value was 1.77nm by using the theoretical relation.
In this paper, the nanocrystalline porous silicon (PS) films are prepared by electrochemical etching of p-type silicon wafer with current density (7 mA/cm2) and etching times on the formation nano-sized pore array with a dimension of around different etching time. The films were characterized by the measurement of XRD, FTIR spectroscopy and atomic force microscopy properties (AFM). We have estimated crystallites size from X-Ray diffraction about nanoscale for porous silicon and Atomic Force microscopy confirms the nanometric size Chemical fictionalization during the electrochemical etching show on the surface chemical composition of PS. The etching possesses inhomogeneous microstructures that contain a -Si clusters (Si3–Si–H) dispersed in amorphous silica matrix . From the FTIR analyses showed that the Si dangling bonds of the as-prepared PS layer have large amount of Hydrogen to form weak Si–H bonds. The atomic force microscopy investigation shows the rough silicon surface, with increasing etching process (current density and etching time) porous structure nucleates which leads to an increase in the depth and width (diameter) of surface pits. Consequently, the surface roughness also increase.
I-V and C-V Characteristics of Porous Silicon Nanostructures by Electrochemical Etching
2013
Porous silicon (PS) layers has been prepared in this work by electrochemic al etching (ECE) technique of a p-type silicon wafer with resistivity (1.5-4 Ω.cm) in hydrofluoric (HF) acid of 20% concentration. Various affecting studied etching time (10, 30, and 45 min) and current density (15 mA/cm 2 ). We have study the morphological properties (AFM) and the electrical properties (I-V and C-V). The atomic force microscopy investigation shows the rough silicon surface, with increasing etching process (etching time) porous structure nucleates which leads to an increase in the depth and width (diameter) of surface pits. Consequently, the surface roughness also increases. The electrical properties of prepared PS; namely current density-voltage characteristics under dark, show that the pass current through the PS layer decreased by increasing the etching time, due to increase the resistivity of PS layer. The PS layer shows a rectifying behaviour with different rectification ratio. C-V measu...
Effect of etching parameter on pore size and porosity of electrochemically formed nanoporous silicon
JOURNAL OF NANOMATERIALS, 2007
The most common fabrication technique of porous silicon (PS) is electrochemical etching of a crystalline silicon wafer in a hydrofluoric (HF) acid-based solution. The electrochemical process allows for precise control of the properties of PS such as thickness of the porous layer, porosity, and average pore diameter. The control of these properties of PS was shown to depend on the HF concentration in the used electrolyte, the applied current density, and the thickness of PS. The change in pore diameter, porosity, and specific surface area of PS was investigated by measuring nitrogen sorption isotherms.
2010
Porous silicon (PS) is defined as a composition of a silicon skeleton permeated by a network of pores or in other word, PS is a network of silicon nanowires and nanoholes which are formed when the crystalline silicon wafers are etched electrochemically in electrolyte solution such as hydrofluoric (HF) acid . PS shows different features in comparison to the bulk silicon such as shifting of fundamental absorption edge into the short wavelength and photoluminescence visible region. The PS material possesses interesting characteristics such as larger surface to volume ratio, high-intensity of nano porous structure and low refractive index. This paper presents the synthesis and characterization of electrochemically anodized PS structures. The effect of short anodization time on the PS structures is investigated. The PS surface morphology and optical properties are characterized using scanning electron microscopy (SEM) and photoluminescence (PL) spectrometer, respectively.
2011
Highly doped n-type porous silicons (PS) were prepared via electrochemical etching. The effect of current density (50 – 300 mA cm-2), etching time (30 – 300 s) and HF concentration (9.2 – 49.0% (v/v)) on the morphology, pore diameter, porosity, surface roughness and electrical properties of the PS were studied. These properties were characterized by Scanning Electron Microscopy (SEM), gravimetric method, Atomic Force Microscopy (AFM) and Current-Voltage (I-V) characteristics. The increment in current density has changed the morphology of the PS from interconnected network to columnar with side branching. However, with the increase in the etching time and HF concentration, this disappeared to give smooth side wall pores
ARTICLE Influence of Current Density on Morphology of Electrochemically Formed Porous Silicon
Jordan Journal of Physics, 2016
Porous silicon samples were prepared by electrochemical anodic etching of p-type silicon wafer in hydrofluoric (HF) acid-based solution. The electrochemical process allowed precise control of porous silicon properties, such as average pore diameter, average pore depth and porosity. The effect of current density on physical properties of porous silicon was investigated by Scanning Electron Microscopy (SEM), I-V characteristics and Fourier Transform Infrared (FTIR) spectroscopy. The average pore diameter and average pore depth were found to increase with the increase in current density. The average pore diameter varied from (10 to 28) nm and the average pore depth varied from (470 to 2200) nm, when the current density was changed from (5 to 36) mA/cm 2 for 10 minutes. In addition, Al/porous/crystalline silicon sandwich showed a good rectification device.
Fabrication of nano-porous silicon using alkali etching process
The best conditions for the production of porous silicon (PS) using alkali etching process have been defined and discussed. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agents were discussed. The main factors which affect the production of porous silicon from crystalline silicon as a result of anisotropic etching are the concentration of etching solution (KOH) and wetting agent (n-propanol), temperature and time of the etching process. Transformation of crystallographic plane of n-Si (2 1 1) to n-PS (1 0 0) is produced by using {(2 wt%) KOH þ (15 vol%) n-propanol} at etching temperature 80 1C and etching time 5 h. These results are confirmed using FTIR which detect the peak at 1015 cm À 1 . A particle size of 15 nm for porous nano-silicon calculated from the XRD data. Pores of (49-349) nm in diameter and 25 mm in depth and a pitch of (4.203 Â 10 À 6 -6.92 Â 10 À 6 ) mm per layer are obtained for the same conditions explained above.