Fitri Suryani Arsyad
Jurusan Fisika, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Sriwijaya

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N-Type Conductivity in Wurtzite Mn-Doped GaN thin Films Grown by Plasma Assisted MOCVD Budi Mulyanti; Agus Subagio; Edi Supriyanto; Heri Sutanto; Fitri Suryani Arsyad; Pepen Arifin; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 2 (2006)
Publisher : Institut Teknologi Bandung

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Abstract

Ferromagnetic semiconductor GaN:Mn thin films were successfully grown by plasma-assisted metalorganic chemical vapor deposition (PA-MOCVD) method on c-plane sapphire substrate. The films were grown at various Mn source flux in the range of 5 - 40 sccm and growth temperature which was lower than that of MOCVD themal, i.e. in the range of 625-700 °C. Cyclopentadienyl manganese tricarbonyl (CpMnT) was used as a source of Mn. X-ray diffraction patterns confirmed that GaN:Mn films are wurtzite and do not show second phase for film with Mn concentration up to 6.4% at 650 °C of growth temperature. Hall effect measurements show n-type characteristics. The carrier (electron) density tends to decreases and Hall mobility tends to with the increase of Mn concentration is increased. Hysteresis curves observed from VSM measurements indicated that all of the samples are ferromagnetic at room temperature.
Pengaruh Bentuk dan Fluktuasi Ukuran Dot terhadap Pelebaran Garis Spektral Inhomogen pada Quantum Dot Gallium Nitrida (QD GaN) Fitri Suryani Arsyad; Budi Mulyanti; Amiruddin Supu; Moehamad Barmawi
Jurnal Matematika & Sains Vol 12, No 4 (2007)
Publisher : Institut Teknologi Bandung

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Abstract

Theoretical analysis of the phenomena of the size fluctuation in Gallium Nitride quantum dot (GaN QD) is presented inthis paper. The effect of QD size fluctuation on the electron and hole energy level and the inhomogeneous linebroadening is studied. Analytical expressions for the inhomogeneous line broadening are derived for a Gaussian sizefluctuation distribution. Decreasing in the QD carrier energy level is observed when QD size increases. The peak ofoptical transition energy probability (Emax) is shifted to higher energy when dot size fluctuation (σL) increases. Theoptical transition energy distribution (fE) of cylindrical QD is at the higher energy with the inhomogeneous linebroadening (σE) wider than those of conical, ellipsoidal, as well as semi ellipsoidal QD.
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)
Publisher : Institut Teknologi Bandung

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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.
PENGARUH PENAMBAHAN IRON MILL-SCALE DAN TEMBAGA SEBAGAI MATERIAL PELAT BIPOLAR Nisya Ulmiah; Fitri Suryani Arsyad; Deni Shidqi Khaerudini
Jurnal Teknosains Vol 7, No 2 (2018): June
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/teknosains.36576

Abstract

Bipolar plate is an important component of proton exchange membrane fuel cell (PEMFC), which provides fuel and oxidant to reactive sites, collect produced current, and mechanical support for the cell in the stacks. This study concerns to find the optimum composition and sintering temperature of iron mills-cale in matrix aluminium as bipolar plate material. This work firstly carried out by downsizing aluminium flake from scrap into powder using high energy milling for 120 min and treated the iron mill-scale at 300 and 1000 oC for 60 min. The waste aluminium powder, after sieving of 150 mesh, was mixing with iron mill-scale containing 30 to 50 vol.% using shaker mill for 10 min. The mixed powders were then pressed 300 MPa and sintered with temperature of 500-600 oC for 60 min and flowed with N2 gas. The structural changes, physical, and mechanical properties of the sintered sample were studied by optical micrograph, density, porosity, hardness Vickers, and electrical conductivity test. The result showed that the optimum composition Fe is 40 vol. % and sinter temperature is 550 oC. Conductivity value of 45.406 S/cm and hardness 183.96 HV hasn’t meet expectation. Cu added containing 4-10 vol. % Fe aims to improve physical properties composites as bipolar plate material PEMFC. The result showed Cu 4 vol. % Fe can increase conductivity value 64.481 S/cm and hardness 340.13 HV.