Samsudi Sakrani

Electrical conductivity measurements in evaporated tin sulphide thin films

Tin sulphide (SnS) has been evaporated on to substrates maintained at fixed temperatures in the range 50-300°C. X-ray diffraction measurements have shown that the films deposited at the lower substrate temperatures are non-stoichiometric, containing higher sulphides of tin, but that those deposited at 300°C consist essentially only of SnS. Film conductivity increased in the range 0·5-20 Sm-1 as the substrate temperature during deposition increased from 50°C to 250°C, this effect being attributed to the changing film composition. Films deposited at 50°C and 150°C showed thermally activated conductivity at temperatures above 220-250 K, with activation energies EB; of 0·12 eV and 014eV, respectively. At lower temperatures both conductivity and activation energy were considerably lower, consistent with hopping via localized states. The conductivity is modified after prolonged cooling to 160K, although the mechanism of this process is not understood

Hydrogenated Amorphous Carbon Films

Hydrogenated amorphous carbon (a-C:H) thin film is one of the most studied materials due to its unique features. The a-C:H thin film is a remarkable material because of its novel optical, mechanical and electrical properties and its similarities to diamond. In this chapter we reviewed the structural and optical properties of hydrogenated amorphous carbon (a-C:H) thin films prepared in a DC-PECVD reactor. Both power and ion bombardment energy were continuously changed during the deposition, as a results of varying deposition parameters such as A.B. Suriani Department of Physics, Faculty of Science and Technology, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak, Malaysia e-mail: absuriani@yahoo.com A.A. Azira NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia e-mail: azira.aziz@gmail.com Putut Marwoto Physics Department, Faculty of Mathematics and Science, Semarang State University, 50229, Semarang, Indonesia e-mail: pmarwoto@yahoo.com S. Sakrani Physics Department, Faculty of Science, Universiti Teknologi Malaysia, 81310, Skudai, Johor, Malaysia e-mail: samsudi@difz2.fs.utm.my Roslan Md. Nor Department of Physics, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia e-mail: rmdnor@um.edu.my M. Rusop NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia e-mail: rusop8@gmail.com Adv Struct Mater, DOI 10.1007/8611_2010_15, # Springer-Verlag Berlin Heidelberg 2010 chamber pressure, electrode distance, CH4 flow rate, and substrate temperature. The films properties ranged from polymer-like to graphite-like a-C:H films, as the power and ion energy increased. The structure and the optical properties of a-C:H films were analyzed by infrared and Raman spectroscopy, UV–Vis Spectrophotometer and photoluminescence. This is to extract the information on sp/sp and hydrogen contents, optical gap, E0 and photoluminescence properties of a-C:H films. The films were found to consist of sp clusters of which the size increases with increasing power and ion bombardment energy during the deposition, resulting in lower hydrogen, sp content, optical gap and photoluminescence response. The increased in hydrogen termination from the films at higher ion energies results in bigger cluster size and produced graphitic films.

The Effect of V/III Ratio on the Crystal Structure of Gallium Arsenide Nanowires

Gallium arsenide (GaAs) nanowires were grown vertically on GaAs (111)B substrate by gold particle-assisted using metal-organic chemical vapour deposition. Transmission electron microscopy and X-Ray diffraction analysis were carried out to investigate the effects of V/III ratio and nanowire diameter on structural properties and crystallinity changes. Results show that GaAs nanowires grow preferably in the wurtzite crystal structure than zinc blende structure with increasing V/III ratio. Additionally, XRD studies have revealed that wurtzite nanowires show prominent peaks especially at (222) orientation. The optimum V/III ratio was found to be 166 with less defect structure, uniform diameter and peak prominence. The nanowires with high quality are needed in solar cells technology for energy trapping with maximum capacity.Keywords : Nanowire; crystal structure; Gallium arsenide; Vapor Liquid Solid

The Effect of Indium Mole Fraction on the Growth Behavior of Your InxGa1-xAs Nanowires (NWs) Grown Using MOCVD

InxGa1-xAs NWs have been grown with various indium mole fractions (x) using MOCVD. The morphology of InxGa1-xAs NWs was observed using Field Emission-Scanning Electron Microscopy (FE-SEM) in order to study the growth behavior of the NWs. FE-SEM results show that the NWs growth mechanism has changed due to changing of indium mole fraction. At low indium mole fraction, the NWs grew via direct impinging mechanism which has produced NWs with relatively uniform diameter. By increasing the value of x the growth mechanism has transformed to the combination of direct impinging and diffusion of source atoms from the surface of substrate causing tapering of NWs. The degree of tapering increases with increasing value of indium mole fraction. InxGa1-xAs NW grown at x = 0.65 has the highest tapering factor, TF = 12.82, whereas NW grown at x = 0.41 has the lowest tapering factor, TF = 2.76.

The Atomic Force Microscope Study of Self-Assembled Silicon Nanodots Growth Using Magnetron Sputtering System

In this paper self-assembled silicon nanodots have been grown on silicon substrate using radio-frequency magnetron sputtering system. This system were settled at varying experimental conditions such as substrate temperature, time of deposition, RF power and fixed argon flow rate. Then the surface roughness was measured by AFM which resulted average dots size of 113 nm. However, the presence of a small amount of grain atoms formed on the surface was confirmed using SEM measurement. The crystalline Si-NDs with (100) plane contributed sharp diffraction peak located at 69.5° was confirmed using XRD measurement. These results of Si-NDs structural properties support the possible growth technique of radio-frequency magnetron sputtering.

The Growth Mechanism of Silicon Nanodots Synthesized by Sputtering Method

Silicon quantum dots have been grown on sapphire substrate using a self‐assembly method of physical vapour deposition. The samples were fabricated at low sputtering rate and varying experimental conditions. Apparently, the onset of nucleation took place during the first 5 minutes of deposition, followed by a further growth of stable islands so‐called nanodots, with the measured radii comparable to the predicted values. Other measurement results confirmed the existence of these dots, including the bandgap energy ∼1.80 eV from PL and a 5% at. silicon from EDX. The nucleation parameters were predicted as follows: Free energy change per unit volume ΔGv∼−2.4×105 Jmol−1; Surface energies per unit area, γLN = 1.48 Jm−2, γNS = 21.6−88.3 Jcm−2 and γLS = 0.82×10−2 Jm−2; Critical energies ΔG* = 6.83×10−16−3.68×10−14 J; Critical radii r* = 20−72 nm. This experimental evidence strongly support the early stage growth model of silicon quantum dot deposited on corning glass substrate.

Study of silicon quantum dots structure growth using radio frequency magnetron sputtering

Nanodots, also known as quantum dots, consist of 100s–1000s of atoms of semiconductor nanoparticles and are approximately 10 – 100 nm in sizes. Silicon nanodots have, in particular, emerged over the last 10 years as a hot area of research due to the fact that a reduction in size of this semiconducting material to the nanometer scale dramatically alters their physical properties.

The structural properties of Sn-doped zinc oxide synthesized by hot-tube thermal evaporation

The growth of Sn:ZnO nanowires on a silicon substrate using a low thermal evaporation method is reported. A horizontal quartz tube with controlled supply of O2 gas were used to fabricate the samples where Zn and Sn metal powders were previously mixed and heated at 500°C. This allows the reactant vapours to deposit onto the substrate, which placed at a certain distance from the source materials. The samples were characterized using FESEM, EDX and HRTEM measurements. Randomly oriented nanowires were formed with varying dopant concentrations from 3 to 15 at%. It was observed that from FESEM images, when the dopant concentrations were increased, a hexagonal rod with a wire extended at its end was clearly formed and the best images of nanowires were shown at the highest concentration of 15 at% measuring between 26 to 35 nm and roughly 500 nm in diameter and length respectively. The doping process played an important role in order to alter the morphological properties of Sn:ZnO nanowires. Sn:ZnO nanowires have large potential in many applications such as in selected sensor technology including gaseous sensors, liquid sensors and others.The growth of Sn:ZnO nanowires on a silicon substrate using a low thermal evaporation method is reported. A horizontal quartz tube with controlled supply of O2 gas were used to fabricate the samples where Zn and Sn metal powders were previously mixed and heated at 500°C. This allows the reactant vapours to deposit onto the substrate, which placed at a certain distance from the source materials. The samples were characterized using FESEM, EDX and HRTEM measurements. Randomly oriented nanowires were formed with varying dopant concentrations from 3 to 15 at%. It was observed that from FESEM images, when the dopant concentrations were increased, a hexagonal rod with a wire extended at its end was clearly formed and the best images of nanowires were shown at the highest concentration of 15 at% measuring between 26 to 35 nm and roughly 500 nm in diameter and length respectively. The doping process played an important role in order to alter the morphological properties of Sn:ZnO nanowires. Sn:ZnO nanowires have ...

Effect of annealing temperature on platinum/YSZ thin film fabricated using RF and DC magnetron sputtering

This research aims to study the growth and the effect of annealing temperature on the structural properties of Platinum/YSZ/Platinum thin film. The thin films were prepared by RF and DC magnetron sputtering method utilized platinum as electrodes (anode and cathode) and YSZ as electrolyte. Two temperatures of annealing (400 and 600 °C) were conducted onto Platinum/YSZ/Platinum thin film for comparison in this study. Crystalline phase, microstructure and thickness of thin films were evaluated using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscope (FE-SEM) technique. Results show that Pt/YSZ/Pt thin film without post-annealing gives a better morphology and crystal phase.

Influence of substrate orientation on the structural properties of GaAs nanowires in MOCVD

In this study, the effect of substrate orientation on the structural properties of GaAs nanowires grown by a metal organic chemical vapor deposition has been investigated. Gold colloids were used as catalyst to initiate the growth of nanowiresby the vapour-liquid-solid (VLS) mechanism. From the field-emission scanning electron microscopy (FE-SEM), the growth of the nanowires were at an elevation angle of 90°, 60°, 65° and 35° with respect to the GaAs substrate for (111)B, (311)B, (110) and (100) orientations respectively. The preferential NW growth direction is always B. High-resolution transmission electron microscope (HRTEM) micrograph showed the NWs that grew on the GaAs(111)B has more structural defects when compared to others. Energy dispersive X-ray analysis (EDX) indicated the presence of Au, Ga and As. The bigger diameter NWs dominates the (111)B substrate surface.