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Journal of Mathematical and Fundamental Sciences
Published by Institut Teknologi Bandung
ISSN : 23375760     EISSN : 23385510     DOI : https://doi.org/10.5614/j.math.fund.sci.
Core Subject : Science, Education,
Astronomy Chemistry Earth & Planetary Sciences Mathematics Physics
Journal of Mathematical and Fundamental Sciences welcomes full research articles in the area of Mathematics and Natural Sciences from the following subject areas: Astronomy, Chemistry, Earth Sciences (Geodesy, Geology, Geophysics, Oceanography, Meteorology), Life Sciences (Agriculture, Biochemistry, Biology, Health, Medical, Pharmacy), Mathematics, Physics, and Statistics.
Arjuna Subject : Matematika - Matematika (Lain-Lain)
Articles 6 Documents
 1 
Search results for , issue "Vol. 40 No. 2 (2008)" : 6 Documents clear
Effect of Growth Temperature and Mn Incorporation on GaN:Mn Thin Films Grown by Plasma-Assisted MOCVD Budi Mulyanti; A. Subagio; F. S. Arsyad; P. Arifin; M. Barmawi; Irzaman Irzaman; Z. Jamal; U. Hashim
Journal of Mathematical and Fundamental Sciences Vol. 40 No. 2 (2008)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2008.40.2.1

Abstract

In this paper, the growth of GaN:Mn thin films by plasma-assisted metalorganic chemical vapor deposition (PAMOCVD) method is reported. The method used in this study, utilizes a microwave cavity as a cracking cell to produce nitrogen radicals, which in turn reduce the growth temperature. Trimethylgallium (TMGa), nitrogen (N2) and cyclopentadienyl manganese tricarbonyl (CpMnT) were used as a source of Ga, N and Mn, respectively, while hydrogen gas was used as a carrier gas for both TMGa and CpMnT. The effect of growth temperature and Mn incorporation on structural properties and surface morphology of GaN:Mn films are presented. The growth of GaN:Mn thin films were conducted at varied growth temperature in range of 625 oC to 700 oC and the Mn/Ga molar fraction in the range of 0.2 to 0.5. Energy dispersive of X-ray (EDX) and X-ray diffraction (XRD) methods were used to analyze atomic composition and crystal structure of the grown films, respectively. The surface morphology was then characterized using both atomic force microscopy (AFM) and scanning electron microscopy (SEM) images. A systematic XRD analysis reveal that maximum Mn incorporation that still produces single phase GaN:Mn (0002) is 6.4 % and 3.2 % for the film grown at 650 oC and 700 oC, respectively. The lattice constant and full width at half maximum (FWHM) of the single phase films depend on the Mn concentration. The decrease in lattice constant accompanied by the increase in FWHM is due to incorporation of substitutional Mn on the Ga sub-lattice. The maximum values of doped Mn atoms incorporated in the wurtzite structure of GaN:Mn as substitutional atoms on Ga sub-lattice are 2.0 % and 2.5 % at 650 oC and 700 oC, respectively. AFM and SEM images show that the film grown at lower growth temperature and Mn concentration has a better surface than that of film grown at higher growth temperature and Mn concentration.
S-Wave Velocity Structure beneath Southwest North America from Seismogram Comparisons of the Mexico Earthquake on 22 June 1997 Bagus Jaya Sentosa
Journal of Mathematical and Fundamental Sciences Vol. 40 No. 2 (2008)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2008.40.2.2

Abstract

This research investigates earth structure beneath the Southwest North America landmass, especially between Mexico and California. Models based on S wave velocities for this area were obtained by carrying out seismogram fitting in time domain and three Cartesian components simultaneously. The data used is from an event, coded as C052297B that occurred in the state of Guerrero, Mexico and it was fitted to synthetic data computed with the GEMINI program at TS network stations. Earth model IASPEI91 and SPREM were used as input to create the synthetic data. Real and synthetic seismograms were subjected to a low-pass filter with a frequency corner of 20 mHz. Waveform analysis results show very unsystematic and strong deviations in the waveform, arrival times, amount of oscillation and the height of the wave amplitude. Discrepancies are met on S, Love, Rayleigh and ScS waves, where the stations epicentral distances are below 300. Deviation in analysis waveform because of the usage of model 1-D of SPREM and IASPEI91, because the 1-D was a kind of average value an elastic property at one particular depth of global earth. With the method of waveform analysis we can see how sensitive waveform is to structures within the layers of the Earth. To explain the discrepancies, a correction to the earth structure is essential. The corrections account for the thickness of the crust, speed gradient of h, the coefficient for the h and v in the upper mantle for surface wave fitting, a small variation of the S speed structure at a layer under the upper mantle above 771 km for S wave fitting, and a small variation at the base the mantle layers for ScS wave fitting. At some stations, a correction for S speed structure have yielded P wave fitting. Results of this research indicate that the 1-D earth model obtained through seismogram fitting at every hypocenter-observation station pair is unique. The Swave velocity on the upper mantle has strong negative anomalies. This paper criticized the previous earth models in the same area, which have been published by other seismologists, by analyzing the seismogram of C052297B earthquake in the TS seismological network station.
The Influence of Silane Gas Flow Rate on Optoelectronic Properties of µc-Si:H Prepared by HWC-VHF-PECVD Technique T. Winata; I. Usman
Journal of Mathematical and Fundamental Sciences Vol. 40 No. 2 (2008)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2008.40.2.3

Abstract

Hydrogenated microcrystalline silicon (µc-Si:H) thin films have been deposited using 10% silane (SiH4) in H2 dilution by Hot Wire Cell Very High Frequency Plasma Enhanced Chemical Vapor Deposition (HWC-VHF-PECVD) technique. The resulted thin film characteristics were systematically studied as a function of the deposition parameter. The previous structural studies showed that the structural phase transition from amorphous to microcrystalline thin film was obtained using the filament temperature of 800 °C. In this study, the optoelectronic properties of µc-Si:H thin films were investigated as a function of the silane gas flow rate from 40 sccm to 80 sccm. The highest deposition rate of 3.6 A/sec and the lower optical bandgap of 1.4 eV were obtained using 80 sccm and 60 sccm of the silane gas flow rate, respectively. The film showed the photosensitivity of 3 x 107, which is quite high above the minimal value of 103 for solar cell application.
AFLP and AMP Fingerprints as Markers to Evaluate Genetic Differences between Medicago truncatula Line Jemalong and 2HA, a New Line Produced by in vitro Culture Selection R. R. Irwanto; R. J. Rose
Journal of Mathematical and Fundamental Sciences Vol. 40 No. 2 (2008)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2008.40.2.4

Abstract

A new line, Medicago truncatula cv. Jemalong 2HA (herein known as 2HA) has been developed via repetitive regeneration and selection of M. truncatula cv. Jemalong. During somatic embryogenesis, 2HA produces 500 times more embryos than its progenitor, Jemalong. It is interesting to study if those two lines are isogenic or has genetic differences. The main objectives of the study was to evaluate the genotypic differences between Jemalong and 2HA also to evaluate the methylation event in 2HA utilized two DNA fingerprinting techniques, i.e AFLP fingerprints (Amplified Length of Polymorphism) and AMP (Amplified Methylation Polymorphism). The results showed that AFLP analysis using eight primers combinations could not detect any differences between Jemalong and 2HA. However, using AMP methylation sensitive primers it could detect 15 polymorphisms out of 840 markers. These results lead to a conclusion that Jemalong and 2HA are isogenic lines. 2HA may have higher regeneration capacities due to methylation process which occurs during the production of 2HA through repetitive regeneration cycles.
Tight Wavelet Frame Decomposition and Its Application in Image Processing Mahmud Yunus; Hendra Gunawan
Journal of Mathematical and Fundamental Sciences Vol. 40 No. 2 (2008)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2008.40.2.5

Abstract

This paper is devoted to the formulation of a decomposition algorithm using tight wavelet frames, in a multivariate setting. We provide an alternative method for decomposing multivariate functions without accomplishing any tensor product. Furthermore, we give explicit examples of its application in image processing, particularly in edge detection and image denoising. Based on our numerical experiment, we show that the edge detection and the image denoising methods exploiting tight wavelet frame decomposition give better results compare with the other methods provided by MATLAB Image Processing Toolbox and classical wavelet methods.
Catalytic Carbon Submicron Fabrication Using Home- Built Very-High Frequency Plasma Enhanced Chemical Vapour Deposition Sukirno Sukirno; Satria Zulkarnaen Bisri; Rasih Yulia Sari; Lilik Hasanah; Mursal Mursal; Ida Usman; Darsikin Darsikin
Journal of Mathematical and Fundamental Sciences Vol. 40 No. 2 (2008)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2008.40.2.6

Abstract

In this research, carbon nanotubes (CNT) fabrication has been tried by using an existing home-made Plasma Enhanced Chemical Vapour Deposition (PECVD) system. The fabrication is a catalytic growth process, whereby a Fecatalyst thin film is grown on the Silicon substrate by using dc-Unbalanced Magnetron Sputtering. Methane (CH4) as carbon source and diluted silane (SiH4) in hydrogen as hydrogen source (ratio 10:1) was used for the CNT fabrication with the Very High Frequency PECVD (VHF-PECVD) method. The fabrication process was executed at the relatively low temperature of 250oC, but with the higher operating plasma frequency of 70 MHz. Recently, a fabrication process with only a single gas source has been carried out as well, but using a modified VHF-PECVD system with an additional hot-wirecomponent. The attempt was done at an higher growth temperature of 400oC. Morphological characterizations, by using Scanning Electron Micrograph (SEM) and Scanning Probe Microscopy (SPM), and composition characterization, by using Energy Dispersion Analysis by X-Ray (EDAX), show convincing results that there are some signatures of CNT present.

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