The Preparation of p-PS and its Photoluminescence Properties

2013 ◽  
Vol 538 ◽  
pp. 81-84
Author(s):  
Lan Li Chen ◽  
Hai Hong Wang ◽  
Ming Ji Shi ◽  
Sheng Zhao Wang ◽  
Wen Fang Si
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Electrochemical Etching ◽  
Volume Ratio ◽  
Blue Shift ◽  
Red Shift ◽  
Luminous Intensity ◽  
Experimental Result ◽  
Anodic Current Density ◽  
Mixed Solution

In this research, p-type porous silicon was successfully fabricated with a typical electrochemical etching method. The mixed solution of HF and absolute ethyl alcohol with different volume ratio was used as the electrolyte in this experiment. The anodic current density was 20 mA/cm2～60 mA/cm2. The luminous intensity of the PS samples increased with the increasing of the current density, the peaks of PL first red shift (from 692.1nm to 727.9nm) then blue shift (from 727.9nm to719.6nm). With the increasing of the concentration of HF, PS luminous intensity gradually decreases, and the peaks of PL gradually occurs red shift. And possible mechanisms of the growth and the photoluminescence of porous silicon were proposed to explain the experimental result．

Origin of Mosaic Structure Obtained During the Production of Porous Silicon with Electrochemical Etching

2019 ◽  
Vol 11 (12) ◽  
pp. 1218-1224
Author(s):  
Dao Tran Cao ◽  
Cao Tuan Anh ◽  
Luong Truc Quynh Ngan
Keyword(s):  
Porous Silicon ◽  
Oxide Layer ◽  
Current Density ◽  
Silicon Oxide ◽  
Electrochemical Etching ◽  
Silicon Layer ◽  
Mosaic Structure ◽  
Anodic Current Density ◽  
Anodic Current ◽  
Silicon Oxide Layer

So far, while producing porous silicon (PSi) with anodic etching of silicon in an aqueous solution of hydrofluoric acid, many researchers (including us) have obtained the crack-into-pieces (or mosaic) structure. Most of the authors believed that the cause of this structure is the collapse and the cracking of the porous, especially highly porous, silicon layer which took place during the drying of PSi after fabrication. However, our study showed that the mosaic structure was formed right during the course of silicon anodization at high anodic current density. Furthermore, our study also showed that at high anodic current density the real silicon etching has been replaced by the growth of a silicon oxide layer. This is a layer of another substance that grows on silicon, so when the layer is too thick (which is obtained when the anodic current density is too high and/or the anodization time is too long) it will crack, creating mosaic pieces. When the silicon oxide layer is cracked, the locations around the cracks will be etched more violently than elsewhere, creating trenches. Thus, the mosaic structure with mosaic pieces emerged between the trenches has formed.

Structural, Surface Morphological and Photoluminescence Properties of Nanostructured Porous Silicon Material for Optoelectronics Application

2012 ◽  
Vol 584 ◽  
pp. 290-294 ◽  
Author(s):  
Jeyaprakash Pandiarajan ◽  
Natarajan Jeyakumaran ◽  
Natarajan Prithivikumaran
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Light Emission ◽  
Electrochemical Etching ◽  
Light Emitting Diode ◽  
Radiative Transition ◽  
Sem Images ◽  
Optoelectronic Application ◽  
Gap Opening ◽  
P Type

The promotion of silicon (Si) from being the key material for microelectronics to an interesting material for optoelectronic application is a consequence of the possibility to reduce its device dimensionally by a cheap and easy technique. In fact, electrochemical etching of Si under controlled conditions leads to the formation of nanocrystalline porous silicon (PS) where quantum confinement of photo excited carriers and surface species yield to a band gap opening and an increased radiative transition rate resulting in efficient light emission. In the present study, the nanostructured PS samples were prepared using anodic etching of p-type silicon. The effect of current density on structural and optical properties of PS, has been investigated. XRD studies confirm the presence of silicon nanocrystallites in the PS structure. By increasing the current density, the average estimated values of grain size are found to be decreased. SEM images indicate that the pores are surrounded by a thick columnar network of silicon walls. The observed PL spectra at room temperature for all the current densities confirm the formation of PS structures with nanocrystalline features. PL studies reveal that there is a prominent visible emission peak at 606 nm. The obtained variation of intensity in PL emission may be used for intensity varied light emitting diode applications. These studies confirm that the PS is a versatile material with potential for optoelectronics application.

Effect of current density on the porous silicon preparation as gas sensors**

2021 ◽  
Vol 30 (1) ◽  
pp. 257-264
Author(s):  
Muna H. Kareem ◽  
Adi M. Abdul Hussein ◽  
Haitham Talib Hussein
Keyword(s):  
Porous Silicon ◽  
Gas Sensors ◽  
Current Density ◽  
Room Temperature ◽  
Low Cost ◽  
High Surface ◽  
Volume Ratio ◽  
Etching Time ◽  
Force Microscopy ◽  
Materials Used

Abstract In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm2 with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm2, reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

Comparative SEM and Cathodoluminescence Microanalysis of Porous GaP Structures

2000 ◽  
Vol 638 ◽  
Author(s):  
M.A. Stevens-Kalceff ◽  
S. Langa ◽  
I.M. Tiginyanu ◽  
J. Carstensen ◽  
M. Christophersen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Current Density ◽  
Electrochemical Etching ◽  
High Current Density ◽  
Anodic Current Density ◽  
High Current ◽  
Induced Voltage ◽  
Current Line ◽  
Anodic Current ◽  
Porous Layers

AbstractElectron microscopy and cathodoluminescence (CL) microanalysis were used for a comparative study of porous layers fabricated by electrochemical etching of n-GaP substrates in a sulfuric acid solution. Both the CL and morphology of porous layers were found to depend upon the anodic current density. At high current density (100 mA/cm2) anodization leads to the formation of so-called current-line oriented pores and an increase in the CL intensity. We observed self-induced voltage oscillations giving rise to a synchronous modulation of the diameter of pores and CL intensity. When the current density decreased to values as low as 1 mA/cm2 the pores began to grow along <111> crystallographic directions and the CL intensity was observed to be lower than that of bulk GaP.

Porous Silicon Multilayer Mirrors and Microcavity Resonators for Optoelectronic Applications

1998 ◽  
Vol 536 ◽  
Author(s):  
S. Chan ◽  
L. Tsybeskov ◽  
P.M. Fauchet
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Current Density ◽  
Silicon Film ◽  
Light Output ◽  
Blue Shift ◽  
Optical Filters ◽  
Multilayer Structures ◽  
Maximum Reflectivity ◽  
The Difference

AbstractPorous silicon multilayer structures are easily manufactured using a periodic current density square pulse during the electrochemical dissolution process. The difference in porosity profile, corresponding to a variation in current density, is attributed to a difference in refractive index. Manipulating the difference in refractive index, high quality optical filters can be made with a maximum reflectivity peak ˜ 100%. The next logical step to further exploit these optical mirrors is to incorporate them into an LED device. The benefit of adding a multilayer mirror below a luminescent film of porous silicon is to significantly reduce the amount of light loss to the silicon substrate and increase the light output. However, oxidation is required to stabilize the as-anodized porous silicon film. This disrupts the overall index profile of the multilayer stack, causing the peak reflectance to blue shift. This phenomenon must be quantified and accounted before device implementation. We present a detailed study on the effects of oxidation temperature, gas environment, and annealing time of porous silicon multilayer structures in a device configuration.

Optimization on Self-Ordering Process of Electropolishing Surface on High-Purity Aluminum

2014 ◽  
Vol 1053 ◽  
pp. 56-60
Author(s):  
Di Ma ◽  
Shu Bai Li ◽  
Xiu Ying Hu ◽  
Xing Hong Zhao ◽  
Xu Hong Chen
Keyword(s):  
Propylene Glycol ◽  
Current Density ◽  
Perchloric Acid ◽  
High Purity ◽  
Volume Ratio ◽  
Limiting Current ◽  
Mixed Solution ◽  
Salt Film ◽  
Limiting Current Density ◽  
High Purity Aluminum

The electropolishing behavior of high-purity aluminum in perchloric acid ethanol electrolytes is studied by the electrochemical methods. The morphologies of electropolished surface are examined by SEM. The results of anodic polarization shows that the limiting current density was decreased with the 1,2-propylene glycol and perchloric acid volume ratio increasing and the temperature decreasing. The results of SEM show that A salt film with porous pores on the electropolishing surface was formed on high-purity aluminum in the mixed solution of 1, 2 propylene glycol and perchloric acid at the volume ratio of 4:1 and 6:1, porosity of film increases from 12.3 % to18.4%, and the pore diameter of film increases from 19 nm to 23 nm with the current density increased from 120 mAcm-2 to 140 mAcm-2.

scholarly journals Fabrication and characterization of porous silicon for humidity sensor application

2019 ◽  
Vol 16 (39) ◽  
pp. 162-170
Author(s):  
Uday M. Nayef
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Humidity Sensor ◽  
Force Measurement ◽  
Electrochemical Etching ◽  
Sample Surface ◽  
Intensity Increase ◽  
Average Pore ◽  
Increase With Increase ◽  
Layer Increase

Porous Silicon (PS) layer has been prepared from p-type silicon by electrochemical etching method. The morphology properties of PS samples that prepared with different current density has been study using atom force measurement (AFM) and it show that the Layer of pore has sponge like stricture and the average pore diameter of PS layer increase with etching current density increase .The x-ray diffraction (XRD) pattern indicated the nanocrystaline of the sample. Reflectivity of the sample surface is decrease when etching current density increases because of porosity increase on surface of sample. The photolumenses (PL) intensity increase with increase etching current density. The PL is affected by relative humidity (RH) level so we can use as humidity sensor. The electrical resistivity has been increased after PS layer formed due to the variation of the pore size and it was much higher after increase etching current.

scholarly journals Responsivity of porous silicon for blue visible light with high sensitivity

2018 ◽  
Vol 16 (37) ◽  
pp. 98-107 ◽  
Author(s):  
Iftikhar M. Ali
Keyword(s):  
Porous Silicon ◽  
Blue Light ◽  
Current Density ◽  
Crystalline Silicon ◽  
Electrochemical Etching ◽  
Etching Time ◽  
Light Illumination ◽  
Average Pore ◽  
Zero Bias ◽  
P Type

In this work, porous silicon (PS) are fabricated using electrochemical etching (ECE) process for p-type crystalline silicon (c-Si) wafers of (100) orientation. The structural, morphological and electrical properties of PS synthesized at etching current density of (10, 20, 30) mA/cm2 at constant etching time 10 min are studied. From X-ray diffraction (XRD) measurement, the value of FWHM is in general decreases with increasing current density for p-type porous silicon (p-PS). Atomic force microscope (AFM) showed that for p-PS the average pore diameter decreases at 20 mA. Porous silicon which formed on silicon will be a junction so I-V characteristics have been studied in the dark to calculate ideality factor (n), and saturation current (Is) for these junctions. These junctions are used in photo sensors applications, where the photo sensors have been examined at blue light region. Sensitivity, rise and fall times have been calculated for this wavelength, the maximum value for sensitivity is (3797.6 %) at etching current density 10 mA/cm2 under blue light illumination at zero bias voltage.

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