Mohamad Barmawi
Kelompok Keahlian Fisika Material Elektronik, Fakultas Matematika dan Ilmu Pengetahuan Alam, ITB

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Karakteristik Film Tipis GaAs yang Ditumbuhkan dengan Metode MOCVD Menggunakan Sumber Metalorganik TDMAAs (Trisdimethylaminoarsenic) Andi Suhandi; Heri Sutanto; Pepen Arifin; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 1 (2005)
Publisher : Institut Teknologi Bandung

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Gallium Arsenide (GaAs) film have been grown by Metalorganic Chemical Vapor Deposition (MOCVD) method on Semi Insulating-Gallium Arsenide (SI-GaAs) substrates using of Trisdimethylaminoarsenic (TDMAAs) and Trimethylgallium (TMGa) precursors. The characteristic of GaAs film strongly depends on growth temperature. The best crystallinity quality of film was obtained at growth temperature, V/III ratio, reactor pressure, N2 and H2 dilute are 580 oC, 4.8, 50 torr, 300 sccm, respectively. X-ray diffraction data indicate that the GaAs films grown at 580 oC show epitaxial layer with FWHM on (200) peak of about 0,477o. Hall effect measurement data indicate that the grown layer were p-type semiconductor, with Hall mobility and carrier concentration in the range of 346 cm2/V.s and 3.17 x 1017 cm-3, respectively. The band gap of GaAs films determined by photoluminiscense (PL) measurement was 1,42 eV. This value is same as the band gap of bulk GaAs.
Fabrication and Characterization of Metal-Semiconductor-Metal n-GaN UV Photodetector by PA-MOCVD Dadi Rusdiana; Sugianto Sugianto; Andi Suhandi; Sukirno Sukirno; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 1 (2005)
Publisher : Institut Teknologi Bandung

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Metal-semiconductor-metal ultraviolet photodetectors fabricated on GaN epitaxial layers grown on (0001) sapphire by plasma-assisted metal organic chemical vapor deposition (PA-MOCVD) method. The photodetector with a thin GaN layer of 0.7 µm exhibited a low dark current with a saturation value of 1.469 x 10-14 A. The responsivity was 0.56 A/W at a wavelength of 320 nm under a bias voltage of 2.5 V.
Efek Magnetisasi Spontan dan Karakteristik Transport Listrik Film Tipis TiO2:Co yang ditumbuhkan dengan Metode MOCVD Horasdia Saragih; Pepen Arifin; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 1 (2005)
Publisher : Institut Teknologi Bandung

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TiO2:Co thin films were grown on Si(100) substrate by MOCVD method. The Co content in the film was varied in the range of 0.73% to 12.19%. The spontaneous magnetization effect and the electrical transport of films were measured by means of a Hall effect measurement. The Hall resistivity as a function of the magnetic field data show that the spontaneous magnetization effect occurs in films at the field lower than 1500 Oe. The Hall resistivity increases with the increase of Co concentration. The measurement of resistivity as function of temperature shows that the films have semiconductive properties. The minimum resistivity increases with increasing Co.
GaN-based Double-hetero Film Grown and Fabricated on (0001) Sapphire Substrates by Plasma-assisted MOCVD Heri Sutanto; Edi Supriyanto; Maman Budiman; Pepen Arifin; Sukirno Sukirno; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 2 (2005)
Publisher : Institut Teknologi Bandung

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GaN-based double-hetero film has been grown on (0001) sapphire substrate by plasma-assisted MOCVD method. The structure of film was n-GaN/Al0.25Ga0.75N/In0.3Ga0.7N/Al0.25Ga0.75N/p-GaN. A photoluminescence (PL) peak originating from InGaN active layer has been observed at room temperature, which produced emission wavelength of 453 nm corresponded to energy of 2.74 eV. However, broadening of the peak caused by the crystalline quality of the InGaN epilayer is still poor, which is related with fluctuation of In rich regions.
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)
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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.
Sifat Listrik Film Tipis SrTiO3 untuk Kapasitor MOS Darsikin Darsikin; Khairurrijal Khairurrijal; Sukirno Sukirno; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 3 (2005)
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Strontium titanate (SrTiO3) film was successfully deposited on a silicon substrate by using a pulsed-laser ablation deposition (PLAD) technique. The optimum temperature is 600o C. The electrical properties measurement was metal-oxide-semiconductor capacitor. The film exhibits good insulating property at room temperature. The fixed charge density and leakage current density were also calculated. The results show that the films have promising applications as alternative gate dielectrics.
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.  
Anisotropi Magnetik Film Tipis TiO2:Co yang Ditumbuhkan dengan Teknik MOCVD Horasdia Saragih; Pepen Arifin; Mohamad Barmawi
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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TiO2:Co thin films have been successfully deposited by using MOCVD technique. The titanium (IV) isopropoxide [Ti(OCH(CH3)2)4] 99,99%, tris (2,2,6,6-tetramethyl-3, 5-heptanedionato) cobalt (III) 99%, and oxygen gas (O2) were used as Ti, Co, and O precursors, respectively. Crystal structure, morphology and magnetic properties of thin films were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM), respectively. The magnetic anisotropy (K) of thin films was very strong depended on the growth temperatures. The thin film grown at temperature of 400°C has anatase-213 structure and K value of 40000 Oe.emu/cm3. At the growth temperature of 450°C, the thin films were has still anatase-213 and K value of 95000 Oe.emu/cm3. At growth temperature of 500°C, the thin films have K value of 72000 Oe.emu/cm3. The crystal structure of films was changed with an additional plane of anatase-301. The thin film grown at temperature of 550°C has K value of 103600 Oe.emu/cm3. The structure of thin film was polycrystalline, mixed by anatase-213, rutile-220 and TiCoO3 (310) phase. All of films have thickness of about 0,7-0,9 µm.
Karakteristik Struktur dan Listrik Film Tipis GaN yang Ditumbuhkan di atas Substrat Si(111) dengan Metode Plasma Assisted-Metalorganic Chemical Vapor Deposition (PA-MOCVD) Heri Sutanto; Agus Subagio; Edi Supriyanto; Pepen Arifin; Sukirno Sukirno; Maman Budiman; Mohamad Barmawi
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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Gallium nitride (GaN) thin films have been grown on Si(111) substrate by PA-MOCVD method, with trimethylgallium (TMGa) and radical nitrogen resulted by plasma of nitrogen gas as a source of Ga and N respectively. The growth was performed at 675 °C; 0.4 torr; 90 sccm and 0.08-0.12 sccm of substrate temperature, reactor pressure, gas flow of nitrogen and TMGa, respectively. The grown polycrystalline GaN thin films have hexagonal structure and n-type semiconductor. The growth rate of the grown thin films increased with increasing gas flow of TMGa. The Hall mobility value of films is still low due to the presence of O and C impurities. The highest value of mobility was found to be 64.88 cm2/V.s with 5.47 x 1018 cm-3 of carrier concentration.
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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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.