S.F.M. Yusop

I-V and Surface Topography Study of Nanostructure Porous Silicon Layer Prepared by Electrochemical Etching

This article reports on the electrical properties of porous silicon nanostructures (PSiNs) in term of its surface topography. In this study, the PsiNs samples were prepared by using different current density during the electrochemical etching of p-type silicon wafer. PSiNs has been investigated its electrical properties and resistances for different surface topography of PSiNs via current-voltage (I-V) measurement system (Keithley 2400) while its physical structural properties was investigated by using atomic force microscopy (AFM-XE100).

Novel Method: Coral Like Structure of Align Carbon Nanotubes (A-CNTs) on Porous Silicon Template (PSiT) without Catalyst; Green Approach

Align Carbon Nanotubes (A-CNTs) is very promising materials and offer attractive applications especially in opto-emission devices and nanoelectronic. Normally CNTs prepared by catalytic chemical vapor deposition using various types of template such as alumina, quartz, silicon and glass template. In this paper, Novel method was introduced to prepare A-CNTs which is combination between immersion and evaporation method. The align CNTs were successfully growth on Porous Silicon template (PSiT) without catalyst. Camphor oil is used as precursor and evaporation temperature is at 800 °C. The PSiT was prepared by photo-electrochemical anodization method. The surface morphology of PSiT layer and A-CNTs were studied using Field Emission Scanning Electron Microscope (FESEM).While Raman spectroscopy will be carried out to study the degree of crystallinity or graphitization of A-CNTs. The growth mechanism will be discussed in this paper. Stubby A-CNTs was successfully growth with 30 nm diameter and 250 nm length on PSiT without metal catalytic process. Meanwhile, this novel technique was found that PSiT is an ideal template for growing A-CNTs without metal catalyst assisted. This novel technique was capable to obtained carbon nanotubes without metal catalyst assisted and improves their purity of product with low cost.

Diameter controlled of carbon nanotubes synthesized on nanoporous silicon support

Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

Structural and Thermal Properties of ACNT by Modified Deposition Method: Growth Time Approach

The knowledge of fabrication method plays an important role in the preparation of aligned carbon nanotubes (ACNT) from natural hydrocarbon feedstock. Here ACNT were successfully synthesized by two-stage catalytic chemical vapor deposition method using organic oil (camphor oil) as a precursor. Synthesis was carried out at a fixed growth temperature of 800 °C and in different growth time: 10, 20, 30, 40, 50 and 60 minutes. The optimized condition for the growth of ACNT produced a small amount of by-product amorphous carbon and highly uniform crystal structure. The experimental results demonstrated that formation ACNT is also dependent on the growth time. The nanotubes were characterized by field emission scanning electron microscopy and micro-Raman spectroscopy. Thermal properties were evaluated by thermogravimetric analysis.

Preparation of silicon quantum dot nanoparticles using free standing porous silicon as base material

Abstract Luminescent silicon quantum dot nanoparticles (SQDNs) have been prepared by photoelectrochemical etching process to produce free standing porous silicon. Following this, the thermomechanical process was used to prepare SQDNs from free standing porous silicon. The samples obtained were characterised using field emission scanning electron microscopy, PL–Raman spectroscopy and Brunauer–Emmett–Teller sorptometry. Structural analysis by field emission scanning electron microscopy revealed the diameter size of SQDNs between 6 and 10 nm, while the Brunauer–Emmett–Teller analysis gave a specific surface area and pore diameter of SQDNs. The PL measurement showed a broad spectrum located at 600–700 nm. A very asymmetric Raman peak is shifted near 500 cm−1, which is due to the reduction in nanocrystal size.

Raman and photoluminescence spectroscopy studies on porous silicon nanostructures

In this work, the study of photoluminescence (PL) and Raman spectroscopy of porous silicon nanostructures (NPSi) have been carried out. The samples were prepared by photo-electrochemical anodization method using p-type silicon wafer based. Photoluminescence measurement of NPSi shows increase of PL intensity and blue shift with increasing of etching time. The varies etching time from 20 min to 40 min produced PL emission at a range of 550–800 nm which is in the range of visible PL band [Fig. 1]. While Raman Spectroscopy measurement shows the spectra were symmetry and broaden when etching time increase from 20 min to 40 min [Fig. 2]. It may due to lattice mismatch strain and part of distortion [1] when porous layer form with increasing the etching time. The photon energy and full half width maximum (FWHM) measurement were carried out to study the optical properties of NPSi which can be used to study the quantum confinement effect.

Effect of Etching Time on Electrical and Optical Properties of Porous Silicon

The characterized on porous silicon layer by using photoluminescence (PL) and I-V measurement (I-V) has been done. Porous silicon was formed by electrochemical etching on (100) p-type Si wafer substrate with the constant current density (20mA/cm2) and variable the etching time. The samples ware prepared under various etching time and properties of porous silicon depend on an etching time. Porous silicon has been used in humidity sensors to detect humidity through changes of its electrical properties. The samples of porous silicon were characterized by using Photoluminescence Spectroscopy (PL) that used to characterize optical properties while I-V Measurement (I-V) used to characterize porous silicon junction properties using a linear voltage source. The result shows PL intensity is increase while the wavelength is decrease for etching time of PSi is longer. For the I-V measurement result shows the etching time affect the resistance of sample due to its porosity.

Electroluminescence and Photoluminescence Properties of Porous Silicon Nanostructures with Optimum Current Density of Photo-Electrochemical Anodisation

P-type silicon wafer ( orientation; boron doping; 0.75 ~ 10 Ω cm-1) was used to prepare samples of porous silicon nanostructures (PSiNs). All samples have been prepared by using photo-electrochemical anodisation. A fixed etching time of 30 minutes and volume ratio of electrolyte, hydrofluoric acid 48% (HF48%) and absolute ethanol (C2H5OH), 1:1 were used for various current densities, J. There were sample A (J=10 mA/cm2), sample B (J=20 mA/cm2), sample C (J=30 mA/cm2), sample D (J=40 mA/cm2) and sample E (J=50 mA/cm2). Photoluminescence (PL) and electroluminescence (EL) spectra were investigated. Maximum peak position of PL spectrum at about ~675 nm, while the maximum EL spectrum at about ~650 nm (which is similar to the PL spectrum).

Surface structural variations of nanostructured porous silicon template formed electrochemically of current density parameter

Nanostructured porous silicon templates (NPSiT) were prepared by photo-electrochemical anodization of p-type crystalline silicon in HF electrolyte at different current density. Five samples were prepared with current densities varied from 5 to 40 minutes at 30 minutes of etching time. The porosity and thickness were measured using the gravimetric method. The surface roughness and topography of porous layers were investigated by atomic force microscopy. The surface roughness, porosity and thickness of porous layers monotonically increase with current densities. The optimum current density of NPSi prepared at optimum etching time (30 minutes) was obtained 20 mA/cm2, that form uniform pores and topography. his electronic document is a “live” template. The various components of your paper [title, text, heads, etc.] are already defined on the style sheet, as illustrated by the portions given in this document.

Photoluminescence Properties of Porous Silicon Nanostructures (PSiNs) with Optimum Electrolyte Volume Ratio of Photo-Electrochemical Anodization

Porous silicon nanostructures light-emitting diode (PSiNs-LED) will be a device for future flat screen display and can be high in demand. Main purpose of this experiment is to determine the photoluminescence properties of porous silicon nanostructures (PSiNs). PSiNs samples were prepared using photo-electrochemical anodization. P-type silicon substrate was used for this experiment. For the formation of PSiNs, a fixed current density (J=20 mA/cm2) and 30 minutes etching time was applied for the variety of electrolyte volume ratio. Volume ratio of hydrofluoric acid 48% (HF48%) and absolute ethanol (C2H5OH), HF48%:C2H5OH, were used for samples 3:1, 2:1, 1:1, 1:2 and 3:1. The effective photoluminescence properties was observed for sample C.