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All Journal Jurnal Ilmu Dasar JURNAL FISIKA Prosiding Universitas PGRI Palembang Jurnal Matematika & Sains GRADIEN JFA (Jurnal Fisika dan Aplikasinya) Jurnal Fisika dan Terapannya
Toto Winata
Institut Teknologi Bandung
Control & Systems Engineering Mathematics Physics

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Aplikasi Metoda Elemen Hingga Dengan Algoritma Crank-Nicolson Dalam Penyelesaian Persamaan Difusi Panas Untuk Pembuatan Sel Surya Silikon Amorf (a-Si) Terpadu Ridwan Abdullah Sani; M. Barmawi; Toto Winata; Sukirno Sukirno
Jurnal Matematika & Sains Vol 1, No 1 (1996)
Publisher : Institut Teknologi Bandung

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The solution of thermal diffusion equation computed numerically by finite element method is used to determine optimum conditions of laser irradiations in the solar cell fabrication. Structure discretization is analyzed in axisymmetric triangular ring elements. The program are codes in written using Fortran 77 language. The Crank-Nicolson algorithm and Fortran 77 IMSL library were used in solving stiffnen matrix equations of the structure. The convergence of the results are shown 50, 98, and 140 elements. The temperature distribution of at the center of laser beam in the all three layers of a-Si solar cells is also shown and superior compared with that of Kishi et al [19].
Optimasi Parameter Tekanan Deposisi pada Penumbuhan Lapisan Tipis Polykristal Silikon dengan Metode Hot Wire Cell PECVD Amiruddin Supu; Ida Usman; Mursal Mursal; Toto Winata; Sukirno Sukirno
Jurnal Matematika & Sains Vol 10, No 1 (2005)
Publisher : Institut Teknologi Bandung

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The Hot wire Cell PECVD method has been developed to grow the poly-Si thin films. The poly-Si thin films were grown on the 7059 corning glass at a filament temperature of 1800 oC. Silane (SiH4) gas 10% diluted in hydrogen (H2) gas was used as gas source. In the hot wire cell PECVD method, reactant gases were decomposed as a result of reaction with a heated filament placed above the substrate and paralel to the gas inlet. The characterization results exhibited that the poly-Si thin films could be grown at the pressure of 200 to 500 mTorr with a substrate temperature of 275 oC. The analysis of XRD result showed that preferential intensity was obtained at the crystal orientation of . The highest values of peak intensity (111 cps), grains size (minor axis 0.5 µm) and dark conductivity (0.60x10-5 Scm-1) were obtained at the deposition pressure of 300 mTorr with deposition rate of 2.2 nm/s.
Study of Pseudostate Expansion in a Simplified Model of Elastic Electron Scattering from Helium Agus Kartono; Toto Winata
Jurnal Matematika & Sains Vol 10, No 2 (2005)
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In this paper, we present a simplified model of electron-helium scattering in which all terms involving nonzero orbital angular momentum are neglected. Elastic scattering cross sections are calculated for this model by using the close-coupling expansion with a non-orthogonal Laguerre-L2 basis function. It is found that the results are in good agreement with experiments and with the other theoretical results.
Analisis Sifat-sifat Optoelektronik Lapisan Tipis Silikon Amorf terhidrogenasi yang ditumbuhkan dengan Teknik VHF-PECVD pada Variasi Daya RF Ida Usman; Amiruddin Supu; Mursal Mursal; Sukirno Sukirno; Toto Winata; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 2 (2005)
Publisher : Institut Teknologi Bandung

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The hydrogenated amorphous silicon (a-Si:H) thin films have been deposited using VHF-PECVD technique. The deposition process was done by varied the rf power from 6 to 12.5 watts with 300 mTorr of chamber pressure and from 20 to 70 watts with 100 mTorr of chamber pressure. The highest deposition rate of 2.99 Å/sec and the highest photoconductivity of 1.13 x 10-4 S/cm were obtained from 8 watts of rf power when the rf power was varied from 6 to 12.5 watts. Then, the highest deposition rate of 9.57 Å/sec was obtained from 40 watts of rf power and the highest photoconductivity of 1.54 x 10-2 S/cm was obtained from 20 watts of rf power when the rf power was varied from 20 to 70 watts. Based on the analysis of characterization results, the degradation of a-Si:H film conductivity was caused by the formation of defect states such as band-tail defect and bandgap defect.
Penumbuhan Lapisan Tipis µc-Si:H dengan Sistem Hot Wire PECVD untuk Aplikasi Divais Sel Surya Syamsu Syamsu; Darsikin Darsikin; Iqbal Iqbal; Jusman Jusman; Toto Winata; Sukirno Sukirno; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 3 (2005)
Publisher : Institut Teknologi Bandung

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Microcrystalline hydrogenated silicon thin films have been grown on corning 7059 by using Hot Wire Plasma Enhanced Chemical Vapor Deposition (PECVD) system. Silane gas dilute in hydrogen gas (SiH4: H2 = 1 : 10 ) used as gas source. The effect substrate temperatures on deposition rate, optical, electrical and structural properties were analyzed. The deposition rate was varied from 3.22-5.24 µm/hour at temperature 175-275o C, SiH4 flow rate of 70 sccm, and filament temperature ~ 1000oC. The optical band gap varied from 1.13-1.44 eV at substrate temperature of 175-275. The Result XRD characterization of µc-Si: H thin film was grown at 275o C shows , , and orientation. Dark conductivities vary from 10-6-10-4 S/cm The Dark conductivity of µc-Si: H is higher than a-Si: H thin film. This result shows that µc-Si: H thin film is possible for p-i-n solar cells device application.  
Pengaruh Daya RF terhadap Kandungan Ge dan Sifat Opto-Elektronik Lapisan Tipis a-SiGe:H Mursal Mursal; Amiruddin Supu; Ida Usman; Toto Winata; Sukirno Sukirno
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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The effect of rf power on Ge content (CGe) and opto-electronic properties of a-SiGe:H thin films deposited by PECVD method had been investigated. a-SiGe:H thin films were grown on corning glass 7059 substrate from a gas mixture of SiH4 and GeH4 10% diluted in H2, respectively. The substrate temperature was kept at 275oC and the rf power was varied from 50 - 120 Watt. The results showed that the CGe of a-SiGe:H thin films decreases with increasing in rf power, and therefore the optical bandgap (Eopt) increases. We found that the optimum rf power was 90 Watt, which corresponds to the highest photo-sensitivity of 1.43 x 104.
Optimization of Deposition Parameters for high Quality a-SiGe:H Thin Films Mursal Mursal; Ida Usman; Toto Winata; Sukirno Sukirno; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 2 (2006)
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The effect of substrate temperature and rf power on the characteristics of a-SiGe:H alloys thin films has been investigated. The a-SiGe:H films made from a mixture of 10% silane (SiH4) and 10% germane (GeH4) gas diluted in hydrogen (H2) were grown on corning glass 7059 by using Plasma Enhanced Chemical Vapor Deposition (PECVD) method. The results showed that the deposition rate of a-SiGe:H films increased with the increasing of substrate temperature and rf power. The optical band gap (Eopt) of the films was improved by increasing of the rf power. The dependency of Eopt on the rf power is attributed to the change in Ge content in the films. The photosensitivity (σph/σd) of the films deposited at 200 °C and 175 °C slightly increased with increasing of rf power from 30-50 Watt. For the films deposited at 225 °C, the photosensitivity increased with increasing of rf power from 30-40 Watt, and relatively constant at rf power of 40-60 Watt.
The Application of Non-orthogonal Laguerre L2 Basis to the Calculation of the Differential and Integrated Cross Sections for the Electron Impact Elastic and Excitation of the 21S, 21P, 23S, 23P States of Helium at Intermediate Energy Agus Kartono; Toto Winata
Jurnal Matematika & Sains Vol 12, No 1 (2007)
Publisher : Institut Teknologi Bandung

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The non-orthogonal Laguerre L2 basis has been applied in the intermediate energy region (30, 40 and 50 eV) for the electron impact elastic and excitation of 21S, 21P, 23S and 23P states of helium. Differential and integrated cross sections are calculated and compared with recent experiments. The results for each case are discussed and compared with other calculation. It is found that the results agree quite well with experiments and with the other results.
Nonuniqueness Solution Forms of Close-Coupling Equations for e-He Scattering Agus Kartono; Toto Winata
Jurnal Matematika & Sains Vol 8, No 3 (2003)
Publisher : Institut Teknologi Bandung

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The close-coupling method relies on the reformulation of the Schrödinger equation into an infinite set of coupledchannel equations by expanding over the complete set of target states. The target states approach will be used is a restricted basis for helium states in which one of the electrons is in a fixed orbital (1s) while the second electron is described by a set of independent L2 functions, thus permitting it to span the discrete and continuum excitations. This type of approximate description of the target should be good for scattering problems in which the dominant reaction mechanism is by one-particle (electron) excitations. We will also show why the standard close-coupling expansion gives rise to nonunique solutions.
Optimasi Parameter Tekanan Deposisi untuk Penumbuhan Lapisan Tipis Mikrokristal Silikon dengan Metode HWC PECVD Amiruddin Supu; I Wayan Sukarjita; Fakhruddin Fakhruddin; Fitri Suryani Arsyad; Toto Winata; Sukirno Sukirno
Jurnal Matematika & Sains Vol 13, No 4 (2008)
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The Hot Wire Cell PECVD method has been developed and successfully applied to grow the hydrogenated microcrystalline silicon ( µc-Si:H) thin films. The µc-Si:H thin films were grown on the 7059 corning glass at a filament temperature of 1000 oC. Ten percents silane (SiH4) gas diluted in hydrogen (H2) gas was used as gas source. In the hot wire cell PECVD method, reactant gases are decomposed as a result of reaction with a heated filament. The filament was placed parallelly with inlet gas system and outside of electrodes. The characterization results exhibited that the deposition rate increased from 1,45 Å/s to 1,56 Å/s with increasing the deposition pressure from 700 mTorr to 1100 mTorr. The SEM image and the XRD spectrum exhibited the transition of amorphous to microcrystalline silicon at an deposition pressure of 1000 mTorr. The transition of amorphous to microcrystalline was indicated by the reduction of amorphous parts and the appearance of peak diffraction at preferential crystal orientation. The dark and photo conductivities of the obtained µc-Si:H thin films was 1,2 x10-5 S cm-1 and 2,12 x 10-3 S cm-1, respectively.
Co-Authors Agus Kartono Altje Latununuwe Amiruddin Supu Andhy Setiawan Aulia Fikri Hidayat Darsikin Darsikin Diky Anggoro Endhah Purwandari Fatimah Arofiati Noor Fitri Suryani Arsyad Hasniah Aliah Hidayat, Aulia Fikri I Wayan Sukarjita Ida Usman Inge M. Sutjahja Iqbal Iqbal Jasruddin Daud Malago Jusman Jusman Kurniati Abidin Laksono Trisnantoro Latununuwe, Altje M. Barmawi Mohamad Barmawi Muhammady, Shibghatullah Mursal Mursal Patricia Lubis, Patricia Ridwan Abdullah Sani Setiawan, Freddy Giovanni Sukirno Sukirno Syamsu Syamsu