Transparent conducting zinc oxide films were grown by metalorganic chemical vapor deposition usin... more Transparent conducting zinc oxide films were grown by metalorganic chemical vapor deposition using diethylzinc/H2O and dimethylzinc/H2O reactant systems. The dimethylzinc/H2 O reactant system was introduced for the first time in this study to grow ZnO films. A very high growth rate of 10 μm/h was obtained. The B2H6 was also employed is an n-type dopant to lower the sheet resistivity of the films. By optimizing the B2H6 flow rate, the films with a sheet resistivity as low as 4 Ω/sq was achieved. The films showed a high transmittance of around 90% in a wavelength range from 400 nm to 1000 nm, suggesting their suitability to be used as transparent conducting materials
We have investigated the characteristic of the dislocations in the ZnO layers grown on c sapphire... more We have investigated the characteristic of the dislocations in the ZnO layers grown on c sapphire by the plasma-assisted molecular beam epitaxy under the different Zn/O flux ratios. The ZnO layers were characterized by the transmission electron microscopy (TEM) and the high-resolution x-ray diffraction (HRXRD). The TEM and HRXRD experiments revealed that the major threading dislocations (TDs) in the ZnO layers are the edge dislocations running along the c axis with Burgers vector of 1/3<11-20>. The TD densities are determined to be 6.9×109, 2.8×109, and 2.7×109 cm-2, for O-rich, stoichiometric, and Zn-rich grown ZnO, respectively. Different from the O-rich grown ZnO where the dislocations run along the c-axis, several dislocations in the stoichiometric and the Zn-rich grown ZnO are inclined to 20°~30° from the c-axis. By considering the slip system in the wurtzite-structure ZnO, the glide planes of the dislocations are close to (10-10) for the O-rich grown ZnO and close to (10-11) for the stoichiometric and Zn-rich grown ZnO. Furthermore, the thickness of the interface dislocations in the O-rich grown ZnO is much thinner than in the stoichiometric and Zn-rich grown ZnO. In addition, the most probable origin of the inclined dislocations including c/a ratios, growth rate, and initial growth stage of high temperature (HT)-ZnO layers are also discussed.
ZnO films on c-sapphire with and without an MgO buffer were grown by plasma-assisted molecular be... more ZnO films on c-sapphire with and without an MgO buffer were grown by plasma-assisted molecular beam epitaxy. ZnO with an MgO buffer was two dimensionally grown, while ZnO without an MgO buffer was grown three dimensionally, which was confirmed by in situ RHEED (reflection high energy electron diffraction) and AFM (atomic force microscopy) observations. Morphology evolution and growth mechanism of an MgO buffer were studied by in situ RHEED observations. Mosaicity (tilt and twist angle), type and density of dislocation were studied by both TEM (transmission electron microscopy) and HRXRD (high resolution x-ray diffraction). Based on in situ RHEED observations, MgO buffer growth involves three important steps including two-dimensional (2D) growth (wetting layer), 2D-3D growth transition and 3D growth. The mechanism of MgO buffer growth can be attributed to three inter-related effects. They are lowering surface energy through a wetting process, creating nucleation sites through a 2D-3D growth transition, and reducing the defect density by introducing dislocation interactions. It was found that the surface morphology and structural properties of the ZnO layers were improved by employing a thin MgO buffer layer grown at around 500 • C followed by high temperature annealing at 800 • C. By introducing an MgO buffer, the formation of 30 • rotational domains in ZnO layers was suppressed, and screw and edge dislocation density of ZnO layers was reduced from 6.1 × 10 8 cm −2 to 8.1 × 10 5 cm −2 and from 1.3 × 10 10 cm −2 to 1.1 × 10 10 cm −2 , respectively.
We have investigated effects of MgO buffer layers and its annealing on the structural quality of ... more We have investigated effects of MgO buffer layers and its annealing on the structural quality of ZnO layers grown on Al O (0001) by plasma assisted molecular beam epitaxy (P-MBE). It was found that surface morphology and crystalline quality 2 3 of ZnO layers were improved by employing thin MgO buffer layers. Furthermore, annealing of the MgO buffer at high temperatures enhanced the surface migration of adatoms, leading to the formation of larger terraces and smoother surface morphology. We speculate that the relaxation of strain in the MgO buffer contributes to lowering of the surface energy. The dislocation density of ZnO layers was also reduced from 5.3=10 cm to 1.9=10 cm by annealing a low temperature (LT) 9
Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan... more Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan validasi proposal. Hmmm… walaupun proposal saya tidak berhubungan dengan bahan campur beton, tapi validasi ini banyak menambah pengetahuan saya tentang Beton. 1. Pasta Pasta adalah campuran air dengan semen. Pasta ini berfungsi sebagai: a. Pengisi pori-pori diantara butiran-butiran agregat halus b. Bersifat sebagai perekat/pengikat dalam proses pengerasan Fungsi tersebutlah yang dapat menyebabkan saling terekatnya butiran2 agregat dengan kuat dan terbentuklah suatu massa yang kompak/padat.
Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan... more Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan validasi proposal. Hmmm… walaupun proposal saya tidak berhubungan dengan bahan campur beton, tapi validasi ini banyak menambah pengetahuan saya tentang Beton. 1. Pasta Pasta adalah campuran air dengan semen. Pasta ini berfungsi sebagai: a. Pengisi pori-pori diantara butiran-butiran agregat halus b. Bersifat sebagai perekat/pengikat dalam proses pengerasan Fungsi tersebutlah yang dapat menyebabkan saling terekatnya butiran2 agregat dengan kuat dan terbentuklah suatu massa yang kompak/padat.
Today’s cryptanalysis on symmetric key cryptography is encouraging the use of larger key sizes an... more Today’s cryptanalysis on symmetric key cryptography is encouraging the use of larger key sizes and complex algorithms to achieve an unbreakable state. However, this leads an increase in computational complexity. This has promoted many researchers to develop high-performance symmetric key cryptography schemes using approaches such as the use of high-end computing hardware. Peer-to-peer (P2P) or enterprise grids are proven as one of the approaches for developing cost-effective high-end computing systems. By utilizing them, one can improve the performance of symmetric key cryptography through parallel execution. This approach makes it attractive for adoption by businesses to secure their documents. In this paper we propose and develop an application for symmetric key cryptography using enterprise grid middleware called Alchemi. An analysis and comparison of its performance is presented along with pointers to future work.
Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan... more Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan validasi proposal. Hmmm… walaupun proposal saya tidak berhubungan dengan bahan campur beton, tapi validasi ini banyak menambah pengetahuan saya tentang Beton. 1. Pasta Pasta adalah campuran air dengan semen. Pasta ini berfungsi sebagai: a. Pengisi pori-pori diantara butiran-butiran agregat halus b. Bersifat sebagai perekat/pengikat dalam proses pengerasan Fungsi tersebutlah yang dapat menyebabkan saling terekatnya butiran2 agregat dengan kuat dan terbentuklah suatu massa yang kompak/padat.
Transparent conducting zinc oxide films were grown by metalorganic chemical vapor deposition usin... more Transparent conducting zinc oxide films were grown by metalorganic chemical vapor deposition using diethylzinc/H2O and dimethylzinc/H2O reactant systems. The dimethylzinc/H2 O reactant system was introduced for the first time in this study to grow ZnO films. A very high growth rate of 10 μm/h was obtained. The B2H6 was also employed is an n-type dopant to lower the sheet resistivity of the films. By optimizing the B2H6 flow rate, the films with a sheet resistivity as low as 4 Ω/sq was achieved. The films showed a high transmittance of around 90% in a wavelength range from 400 nm to 1000 nm, suggesting their suitability to be used as transparent conducting materials
We have investigated the characteristic of the dislocations in the ZnO layers grown on c sapphire... more We have investigated the characteristic of the dislocations in the ZnO layers grown on c sapphire by the plasma-assisted molecular beam epitaxy under the different Zn/O flux ratios. The ZnO layers were characterized by the transmission electron microscopy (TEM) and the high-resolution x-ray diffraction (HRXRD). The TEM and HRXRD experiments revealed that the major threading dislocations (TDs) in the ZnO layers are the edge dislocations running along the c axis with Burgers vector of 1/3<11-20>. The TD densities are determined to be 6.9×109, 2.8×109, and 2.7×109 cm-2, for O-rich, stoichiometric, and Zn-rich grown ZnO, respectively. Different from the O-rich grown ZnO where the dislocations run along the c-axis, several dislocations in the stoichiometric and the Zn-rich grown ZnO are inclined to 20°~30° from the c-axis. By considering the slip system in the wurtzite-structure ZnO, the glide planes of the dislocations are close to (10-10) for the O-rich grown ZnO and close to (10-11) for the stoichiometric and Zn-rich grown ZnO. Furthermore, the thickness of the interface dislocations in the O-rich grown ZnO is much thinner than in the stoichiometric and Zn-rich grown ZnO. In addition, the most probable origin of the inclined dislocations including c/a ratios, growth rate, and initial growth stage of high temperature (HT)-ZnO layers are also discussed.
ZnO films on c-sapphire with and without an MgO buffer were grown by plasma-assisted molecular be... more ZnO films on c-sapphire with and without an MgO buffer were grown by plasma-assisted molecular beam epitaxy. ZnO with an MgO buffer was two dimensionally grown, while ZnO without an MgO buffer was grown three dimensionally, which was confirmed by in situ RHEED (reflection high energy electron diffraction) and AFM (atomic force microscopy) observations. Morphology evolution and growth mechanism of an MgO buffer were studied by in situ RHEED observations. Mosaicity (tilt and twist angle), type and density of dislocation were studied by both TEM (transmission electron microscopy) and HRXRD (high resolution x-ray diffraction). Based on in situ RHEED observations, MgO buffer growth involves three important steps including two-dimensional (2D) growth (wetting layer), 2D-3D growth transition and 3D growth. The mechanism of MgO buffer growth can be attributed to three inter-related effects. They are lowering surface energy through a wetting process, creating nucleation sites through a 2D-3D growth transition, and reducing the defect density by introducing dislocation interactions. It was found that the surface morphology and structural properties of the ZnO layers were improved by employing a thin MgO buffer layer grown at around 500 • C followed by high temperature annealing at 800 • C. By introducing an MgO buffer, the formation of 30 • rotational domains in ZnO layers was suppressed, and screw and edge dislocation density of ZnO layers was reduced from 6.1 × 10 8 cm −2 to 8.1 × 10 5 cm −2 and from 1.3 × 10 10 cm −2 to 1.1 × 10 10 cm −2 , respectively.
We have investigated effects of MgO buffer layers and its annealing on the structural quality of ... more We have investigated effects of MgO buffer layers and its annealing on the structural quality of ZnO layers grown on Al O (0001) by plasma assisted molecular beam epitaxy (P-MBE). It was found that surface morphology and crystalline quality 2 3 of ZnO layers were improved by employing thin MgO buffer layers. Furthermore, annealing of the MgO buffer at high temperatures enhanced the surface migration of adatoms, leading to the formation of larger terraces and smoother surface morphology. We speculate that the relaxation of strain in the MgO buffer contributes to lowering of the surface energy. The dislocation density of ZnO layers was also reduced from 5.3=10 cm to 1.9=10 cm by annealing a low temperature (LT) 9
Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan... more Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan validasi proposal. Hmmm… walaupun proposal saya tidak berhubungan dengan bahan campur beton, tapi validasi ini banyak menambah pengetahuan saya tentang Beton. 1. Pasta Pasta adalah campuran air dengan semen. Pasta ini berfungsi sebagai: a. Pengisi pori-pori diantara butiran-butiran agregat halus b. Bersifat sebagai perekat/pengikat dalam proses pengerasan Fungsi tersebutlah yang dapat menyebabkan saling terekatnya butiran2 agregat dengan kuat dan terbentuklah suatu massa yang kompak/padat.
Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan... more Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan validasi proposal. Hmmm… walaupun proposal saya tidak berhubungan dengan bahan campur beton, tapi validasi ini banyak menambah pengetahuan saya tentang Beton. 1. Pasta Pasta adalah campuran air dengan semen. Pasta ini berfungsi sebagai: a. Pengisi pori-pori diantara butiran-butiran agregat halus b. Bersifat sebagai perekat/pengikat dalam proses pengerasan Fungsi tersebutlah yang dapat menyebabkan saling terekatnya butiran2 agregat dengan kuat dan terbentuklah suatu massa yang kompak/padat.
Today’s cryptanalysis on symmetric key cryptography is encouraging the use of larger key sizes an... more Today’s cryptanalysis on symmetric key cryptography is encouraging the use of larger key sizes and complex algorithms to achieve an unbreakable state. However, this leads an increase in computational complexity. This has promoted many researchers to develop high-performance symmetric key cryptography schemes using approaches such as the use of high-end computing hardware. Peer-to-peer (P2P) or enterprise grids are proven as one of the approaches for developing cost-effective high-end computing systems. By utilizing them, one can improve the performance of symmetric key cryptography through parallel execution. This approach makes it attractive for adoption by businesses to secure their documents. In this paper we propose and develop an application for symmetric key cryptography using enterprise grid middleware called Alchemi. An analysis and comparison of its performance is presented along with pointers to future work.
Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan... more Posted in: Teknik Sipil. 11 komentar Tepatnya hari Jum'at tanggal 29 Oktober 2010. Saya melakukan validasi proposal. Hmmm… walaupun proposal saya tidak berhubungan dengan bahan campur beton, tapi validasi ini banyak menambah pengetahuan saya tentang Beton. 1. Pasta Pasta adalah campuran air dengan semen. Pasta ini berfungsi sebagai: a. Pengisi pori-pori diantara butiran-butiran agregat halus b. Bersifat sebagai perekat/pengikat dalam proses pengerasan Fungsi tersebutlah yang dapat menyebabkan saling terekatnya butiran2 agregat dengan kuat dan terbentuklah suatu massa yang kompak/padat.
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