Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Porous Silicon


Synthesis of Porous Silicon by Electrochemical Etching for Gas Sensor Application

Duha H. Jwied; Uday M. Nayef; Falah AH Mutlak

Engineering and Technology Journal, 2022, Volume 40, Issue 4, Pages 555-562
DOI: 10.30684/etj.v40i4.2064

In the present study, the layers of porous Silicon (PS) have been produced from the p-type Silicon with a (100) orientation using the approach of electrochemical etching. The samples were anodized in a solution of HF concentration 18% and 99% C2H2OH. Samples characteristics of PS were studied by etching time constant (15 min). In addition, the alteration of the current density value into (5, 10,15,20, and 25) mA/ cm2 was also studied. Samples were characterized by nanocrystalline porous Silicon via X-Ray Diffraction (XRD). The AFM (Atomic force microscope) analysis of PS shows the sponge-like structure. Also, a 39.76 nm average diameter was coordinated in the rod-like temperature variation, fabricated from prepared samples on the sensor's sensitivity, recovery time, and response time. The maximal level of the sensitivity has been approximately (20,11)% for porous Silicon of gas NO2 and NH3, respectively.

Synthesis and Study of Modified Nanostructure Porous Silicon Layers for Chemical Gas Sensing

A.D.Thamir; A. L. Abed; F. Q. Mohammed; A. S. Hasan

Engineering and Technology Journal, 2017, Volume 35, Issue 10, Pages 970-974

In this work, We prepared a modified nanostructure porous silicon (PS) layers for effective chemical gas sensing. Nanopore covered microporous silicon gas sensor has been fabricated using electrochemical etching in an HF acid and ethanol solution. A porous silicon (PS) surface has been modified using selective depositions formed from metal to enhance the response to Sensing of CO2. (PS) has been interest for gas sensing because of the exceptional gathering of importent features. By setting the process parameters,the porosity, pore size, and the morphology can be modifid and practically controlled. The modified porous silicon layers were characterized using different techniques such as scanning electron microscopy(SEM)and a series of electrical characterizations to study the structures in the contact of the carbon dioxide was achieved.

Preparation and Characterization Study of Porous Silicon Doped with Cu and Ag

U. M. Nayef; A.M. Abdul Hussein; A. J. Kata

Engineering and Technology Journal, 2017, Volume 35, Issue 1, Pages 8-12

In this paper, porous silicon was prepared by using electrochemical etching technique of p-type silicon acceptor, with a resistivity of 1.5-4Ohm.cm, using hydrochloric acid with concentration of 24%. The etching current density effect 4, 12, 20mA/cm2 was carried out at constant etching time of 15min. The structural characteristics of the porous silicon and the doped porous silicon were studied and found an expansion in the spectrum of the X-rays and a simple shift in the diffraction angles while maintaining the surface direction (111). The morphological properties were studied using the atomic force microscope which showed pores formation and gives the pore diameter within the range of 19.08 to 44.73nm for the prepared samples. It was also noted that the rate of pore diameter and the thickness of the porous silicon layer increased with increasing etching current density. Electrical characteristics of the nanoscale porous silicon layer and the doped porous silicon with silver and copper showed that Current-Voltage (I-V) characteristics of the prepared samples to be a rectifying behavior. An improvement in the electrical characteristics of the doped porous silicon samples was observed

Hydrogen Gas Sensor of ZnO Doping with CuO/PS Nanocomposite

Isam M. Ibrahim; Shahad I.sharhan; Fuad T.ibrahim

Engineering and Technology Journal, 2015, Volume 33, Issue 6, Pages 1093-1101

Pulse laser deposition was used in this research by Nd:YAG laser with (λ=1064 nm average frequency 6 Hz and pulls duration 10 nm) to deposit an adopedZnO thin films with 0.02CuO with thickness (100) nm. X-ray diffraction pattern for Zinc oxide films with doping ratio of CuO shows that these films have polycrystalline hexagonal structure, and the X-ray diffraction patterns of porous silicon showed a broadening in the FHWM with increasing etching time. .From atomic force microscope of prepared samples show an average diameter of PS nanostructure. The operation temperature of gas sensor was studied for different temperature and found that the maximum sensitivity is (67.55) at T=350 cº.

Investigation of Laser Assisted Etching for Preparation Silicon Nanostructure and Diagnostic Physical Properties

Zahraa J. Abdulkareem; Uday M. Nayef; Kadhim A.Hubeatir

Engineering and Technology Journal, 2015, Volume 33, Issue 4, Pages 595-601

In this paper; nanostructure porous silicon (PS) was prepared by using photo-electrochemical etching (PECE) of n-type silicon at 10 & 30 mA/cm2 etching current density for 10 minute. X-ray diffraction (XRD) confirms the formation of porous silicon and the crystal size is reduced toward nanometric scale. The Atomic Force Microscope (AFM) investigation shows the sponge like structure of PS, the width of surface pits and surface roughness increase with etching current density.Finally, the Fourier Transform Infrared (FTIR) illustrates the PS layer have large amount of dangling bonds.

Structural,Morphology and PL Properties of ZnO Film Deposition on Porous Silicon

Uday Muhsin Nayef; Mohammed Waleed Muayad

Engineering and Technology Journal, 2014, Volume 32, Issue 6, Pages 1106-1110

ZnO thin film was deposited on glass and porous silicon by spray pyrolysis technology with fixed parameters consist (substrate temperature 400Co, deposition rate 100nm/min), and the measurements of structural (XRD), morphology (AFM) and photoluminesces (PL) refer to good growth of ZnO after using porous silicon more than using glass and that's come from sponge like structure of porous silicon and large spastic area of porous silicon (about 500m2/cm3).

Preparation and Characterization of Porous Silicon Prepared by Electrochemical Etching

Adawiya J .Haider; Jassim M. Abass; Omar abdulkreem

Engineering and Technology Journal, 2014, Volume 32, Issue 4, Pages 623-628

Porous silicon (PS) layers were formed on p-type silicon (Si) wafers by using electrochemical etching method. The influence of varying etching time in the anodizing solution ,on structural and optical properties of porous silicon has been investigated. Additionally , the thickness and porosity of the layers were measured using the gravimetric method. The surface morphology was studied by Scanning Electron Microscope (SEM). Finally, the optical properties of porous silicon on silicon substrates were investigated by employing photoluminescence (PL).

Etching Rate Enhancement of Porous Silicon Produced by Lasers

Mohammed A. Ibrahem

Engineering and Technology Journal, 2012, Volume 30, Issue 4, Pages 628-633

Two laser systems work with different operational modes have been used to
produce silicon nanostructure surfaces. Pulsed Nd:YAG laser has been employed to
produce silicon textured surface which containing nano/microstructures. Effects of
laser energies (80 – 200) mj were examined to produce surface of different structures.
While Diode laser (532 nm) of fixed power (50 mW) was used in the second stage to
modify the porous structure over the textured surface. The effect of different surface
morphology on the laser induced etching process was studied using atomic force
microscope (AFM) and an image processing program to sketch the surface plot to the
samples depending on the optical microscope photos. The photoluminescence spectra
have been utilized to study the nanocrystallite size distribution in porous silicon, it
shows high peak position lies in (2 - 2.1) eV.

Omnidirectional Mirrors for Porous Silicon Multilayer by Electrochemical Etching

Uday Muhsin Nayef

Engineering and Technology Journal, 2011, Volume 29, Issue 15, Pages 3185-3193

The measurements and calculations of monolayer and multilayer reflectance, made of porous silicon films, have been carried out. The multilayer component has been made of porous silicon layers that has refractive indices of nA=2.16 and nB= 1.55. The band structure of one dimensional photonic crystal has been calculated using the transfer
matrix method which consists of alternative layers of two dielectric materials A and B. As for the multi layers component which are consist of the periodical repetition of two layers of different refractive indices (nH and nL) which has an omnidirectional photonic
band gap (PBG), the width of which depends on the incidence medium and on the refractive index ratio nH/nL. In porous silicon, this ratio is limited by the material and fabrication characteristics. Theoretical and experimental study has been carried on the wide range of practical fabrication parameters for the formation of omnidirectional PBG.
A band width of 400 nm is corresponding to a reflectivity higher than 97% which is suitable for applications of omnidirectional PBG at wavelength 1550 nm.

Effect of HF Concentration on the PS Structures Prepared by Photoelectrochemical Etching

Yasmeen Z. Dawood; Bassam G. Rasheed; Ali H. AL-Hamdani

Engineering and Technology Journal, 2010, Volume 28, Issue 11, Pages 2143-2150

Porous silicon was fabricated at p-n junction wafer by
photoelectrochemical (PEC) etching. Silicon wafer with various electrolyte
containing different HF concentrations was used to explain PS formation by the
reaction at the Si/ electrolyte interface. An investigation of the dependence on HF
concentration to formed PS layer was made. The surface morphology of PS layer
was study as a function of HF concentration. Pillar like structures are formed at
low HF concentration and pores structures are obtained a at higher HF
concentration (40%). The etching rate increases with increasing HF concentration
causing faster silicon dissolution. Thus the total pillar volume would increase by
increasing the HF concentration.

Effect on Rapid Thermal Oxidation process on Electrical Properties of Porous Silicon

Maysaa A.Mohamed; Amany A. Awaad; Khawla S. Khashan

Engineering and Technology Journal, 2009, Volume 27, Issue 4, Pages 663-674

In this work, the porous silicon was prepared by using stain etching in HF-HNO3 at
different etching times. Then Rapid Thermal Oxidation (RTO) processes were used for
surface treatment at different temperature and oxidation time to enhancement sample
properties. Fourier Transforms infrared (FTIR) spectrum exhibit the formation of SiHx
(x=1, 2) and Si-O bonds which indicate the present of porous structure and formation of
oxidation porous layer. The Capacitance – Voltage characteristics reveal that effective
carrier density is 36*1015 cm-3 for sample etching time at 2min, while there was a
change from (37.8*1015 to 45.7*1015) cm-3 for sample oxidation at different oxidation
temperature (373 – 973)K and from (38.2*1015 to 40*1015) cm-3 for sample oxidation at
different oxidation time (0.5 – 3.5)min. Also the porosity was (45.56%) for PS/p-Si
etching at 2min while reduce from (45% to 35.4%) with oxidation temperature, and from
(44.2% to 40.5%) with oxidation time. From photocurrent characterized, that the
photosensitivity for PS/p-Si structure is better where etching time at 2min, and its 0.2545
A/W at 370nm, and it increased after Rapid Thermal Oxidation (RTO) from (0.34 to
0.44) A/W with different oxidation temperature, and changed from (0.35 to 0.34) A/W
with different oxidation time, so that sandwich hetrojunction exhibit good efficiency
photodiode.