Mauludi Ariesto Pamungkas | Universitas Brawijaya (original) (raw)

Papers by Mauludi Ariesto Pamungkas

Journal of Nanoscience and Nanotechnology, 2013

We have studied the very early stage of the room temperature oxidation of the externally-strained... more We have studied the very early stage of the room temperature oxidation of the externally-strained Si(001) surface using molecular dynamics simulation. It was found that the different treatment history of the sample under the same strain resulted in the difference in the number density of dimer. The as-prepared samples of different treatment history with 12.15% strain were used to investigate the initial oxidation behavior of Si(001). 500 times of independent deposition of single oxygen molecule onto the random position of clean Si(001) surface was simulated. Oxidation behavior was statistically analyzed for various dimer density of the surface which is dependent on strain-treatment history. Oxygen uptake and penetration depth profile showed an important role of dimers on the surface oxidation behavior.

Journal of Applied Physics, 2013

We have investigated the initial stage of oxidation of Si (001) surface by water (H 2 O) molecule... more We have investigated the initial stage of oxidation of Si (001) surface by water (H 2 O) molecules using reactive molecular dynamics (MD) simulation at 300 K and 1200 K without any external constraint on the water molecules. Previously, reported water reaction behaviors on silicon surface by ab initio calculations or experimental observations were reproduced by the present MD simulation. The present simulation further revealed that the hydrogen atom in H 2 O is more attractive than oxygen atom in O 2 to bond with Si, such that it accelerates the dissociation process of H 2 O. It was also observed that the oxidation reaction was enhanced with increased number of the supplied water molecules. It was suggested that the repulsion between water molecules and their fragments facilitates the dissociation of both water molecules and hydroxyl decomposition on the Si surface. Therefore, the wet oxidation behavior appeared to have more temperature dependence even in the early stage of oxidation. V

Sifat elektronik dari Silikon dua dimensi berbentuk heksagonal yang disebut silicene telah diteli... more Sifat elektronik dari Silikon dua dimensi berbentuk heksagonal yang disebut silicene telah diteliti dengan pendekatan teori kerapatan fungsional. Silicene diprediksi memiliki nilai konstanta kisi ( lattice constant) sebesar 3,9 Angstrom, nilai ini mendekati hasil dari eksperimen. Silicene diprediksi memiliki sifat elektronik yang mirip dengan graphene. Pita energi silicene diprediksi tidak memiliki celah energi dan tidak saling tumpang tindih, banyaknya keadaan yang dominan adalah pada orbital p dan struktur membentuk ikatan kovalen.

EFEK DOPING ATOM ARSENIK PADA PITA ENERGI MATERIAL SILICENE BERDASARKAN PERHITUNGAN TEORI KERAPAT... more EFEK DOPING ATOM ARSENIK PADA PITA ENERGI MATERIAL SILICENE BERDASARKAN PERHITUNGAN TEORI KERAPATAN FUNGSIONA L . Menyusul sukses graphene dengan sifat-sifatnya yang super dan unik, material dua dimensi yang strukturnya serupa dengan graphene menjadi pusat perhatian para peneliti material. Silicene sebagai material yang memiliki struktur kristal sama dengan graphene namun terdiri dari atom-atom silicon menjadi material yang sangat penting mengingat dominasi silicon sebagai bahan utama komponen elekronika. Struktur pita dari silicene murni dan yang di doping dengan atom As diteliti dengan metode teori kerapatan fungsional (Density Functional Theory). Atom As disimulasikan pada beberapa posisi yang paling mungkin. Berdasarkan perhitungan energi pembentukan, posisi substitusi adalah posisi yang paling stabil dari atomAs pada silicene. Posisi atom As tepat di atas atom silkon jauh lebih stabil dari posisi di atas hexagonal (posisi hollow). Hasil perhitungan struktur pita menunjukkan bah...

MATEC Web of Conferences, 2015

Following the success of graphene which possesses unique and superior properties, 2D material oth... more Following the success of graphene which possesses unique and superior properties, 2D material other than graphene become centre of interest of material scientists.Silicene, which has the same crystal structure as graphene but consist of silicon atoms rather than carbon become intriguing material due to domination of silicon as main material of electronic component. It is common to enhance electronic properties of semiconductor by adding dopant atoms. The electronic properties of Silicene doped with Gallium are investigated using first principle calculation based on density functional theory (DFT).Ga doping changes character of silicene from semimetal to conductor except silicene with Ga doping on S-site (Ga atom substitutes one Si atom) which lead to semiconductor.

Journal of Applied Physics, 2011

Initial stage of oxidation of Si (100) surface by O 2 molecules was investigated in atomic scale ... more Initial stage of oxidation of Si (100) surface by O 2 molecules was investigated in atomic scale by molecular dynamics (MD) simulation at 300 K and 1200 K without external constraint on the oxygen molecules. A reactive force field was used for the simulation to handle charge variation as well as breaking and forming of the chemical bonds associated with the oxidation reaction. Results of the present simulation are in good agreement with previous first principle calculations and experimental observations: the oxygen molecules spontaneously dissociated on the Si (100) surface and reacted with Si first layer without energy barrier. The simulation also exhibited that the reacted oxygen preferentially located in the back bonds of the surface dimer. Consecutive oxidation simulation with 300 O 2 molecules showed that the diffusion of oxygen atom into the subsurface of clean Si surface can occur during very short time of the present oxidation simulation. The present MD simulation also revealed that the oxidation at 300 K results in more stoichiometric oxide layer than that at 1200 K. V

Applied Physics Letters, 2011

World Academy of Science, Engineering and Technology, International Journal of Materials and Metallurgical Engineering, 2015

Very initial stage of oxidation process of Si (001) surface at room temperature (300 K) and high ... more Very initial stage of oxidation process of Si (001) surface at room temperature (300 K) and high temperature (1200 K) was investigated using large scale molecular dynamics simulation. Reactive force field potential [1] was used for the simulation owing to its ability to handle charge variation as well as breaking and forming of bonds associated with the oxidation reaction. The results show that oxygen molecules adsorb dissociatively or otherwise leave the silicon surface. Initial position and orientation of oxygen molecule above the surface play important role in determining final state and time needed to dissociate. At 300 K, continuous transformation of ion Si (or suboxide Si2O) to Si2 (SiO), Si3 (Si2O3) and finally to Si4 (SiO2) clearly observed. High temperature silicon surface provide heat energy that enable oxygen atom to penetrate into deeper silicon surface. The heat energy also retards adsorption process. As a result, transformation of ion Si is impeded at 1200 K.

Since silicon nitride (SiN x ) film is more stable than SiO 2, silicon nitride, thus it is widely... more Since silicon nitride (SiN x ) film is more stable than SiO 2, silicon nitride, thus it is widely used in semiconductor industry as an insulatorlayer. The study of nitrogenation process of a-Si was performed using molecular dynamics simulations to determine the properties of the bonds created in the structure of a-SiNx. Reactive force field (Reaxff) was used as potential in this molecular dynamic simulation owing to its ability to describe charge transfer as well as breaking and formation of atomic bonds. The structure of a-Si is obtained by melting the crystalline silicon at temperature of 3500 K followed by quenching to room temperature. The nitrogenation process was carried out by randomly distributing 900 N atoms over the a-Si surface for 60 ps at temperature varied from 300 K, 600 K, 900 K, and 1200 K. The higher the temperature nitrogenation applied in the system, the more number of N atoms adsorbed, resulting in a deeper penetration depth of Nitrogen atom. Amorphization and n...

The Zinc oxide is well known as a direct wide bandgap semiconductor material with many promising ... more The Zinc oxide is well known as a direct wide bandgap semiconductor material with many promising properties for blue/UV optoelectronics, transparent electronics, spintronic devices and sensor applications. Controllable bandgap tuning is important to widen its possible applications. In the present work, we applied density functional theory to study bandgap tuning of ZnO by introducing Na atom and Cl atom. Sodium acts as p-type doping, while chlorine acts as n-type doping for ZnO. The effect of Na and Cl doping in the study was calculated using the Density Functional Theory (DFT) method. The results indicate that ZnO, which is a natural n type semiconductor when doped with p type, has an increase in bandgap, on the contrary, doping with n type decreased its bandgap

Journal of Physics: Conference Series

A Stanene, is a two-dimensional material composed of tin atoms arranged in a single hexagonal lay... more A Stanene, is a two-dimensional material composed of tin atoms arranged in a single hexagonal layer, in a manner similar to graphene. First principle studies based on density functional theory were performed to investigate the effects of hydrogenation and Al/P doping on electronic structure and magnetic properties of stanene. Hydrogenation opens the bandgap of stanene and changes it from nonmagnetic to the ferromagnetic material through H 1s states and Sn 5p states hybridization. Al/P atom at hollow site prevent electrons of adjacent Sn atoms to connect so that inducing unpaired electrons. The combination of hydrogenation and Al/P doping increases its magnetization. The sequence based on its magnetic moment from small to large is as follows: pure stanene, Al-doped stanene, P-doped stanene, hydrogenated stanene, Al-doped hydrogenated stanene, and P-doped hydrogenated stanene. The controllable transformation from nonmagnetic metallic to a magnetic semiconductor is a key requirement fo...

Jurnal Sains Materi Indonesia

SIMULASI DINAMIKA MOLEKULAR REAKTIF PROSES AMORFISASI SILIKON KRISTAL. Silikon kristal dan silico... more SIMULASI DINAMIKA MOLEKULAR REAKTIF PROSES AMORFISASI SILIKON KRISTAL. Silikon kristal dan silicon amorf adalah material utama yang digunakan untuk bahan solar sel. Silikon amorf lebih mudah dibuat dan lebih murah dibandingkan silikon kristal namun efisiensi silikon amorf masih lebih rendah dibanding silikon kristal. Untuk meningkatkan sifat listrik dari silikon amorf diperlukan pengetahuan strukturmikro silikon amorf yang terbentuk dari amorfisasi silikon kristal. Oleh karena itu dilakukan simulasi dinamika molekuler untuk meneliti proses amorfisasi silikon kristal. Proses amorfisasi dilakukan dengan cara yang menyerupai proses dalam eksperimen, yaitu pemanasan sampai silikon kristal mencair kemudian dilanjutkan dengan pendinginan yang cepat sehingga tidak cukup waktu untuk atom-atomnya membentuk struktur yang teratur. Setelah beberapa suhu dan kecepatan pendinginan dicoba, didapati bahwa dengan pemanasan sampai 3500 K dan dengan laju pendinginan 10 14 K/s silikon amorf terbentuk. Pada suhu yang terlalu tinggi, sistem menjadi rusak, sedangkan pada suhu yang terlalu rendah tidak terjadi perubahan fase. Proses amorfisasi disertai dengan meningkatnya panjang rata-rata ikatan dari ikatan 4-4 fold, 4-5 fold, dan 5-5 fold secara berurutan. Selain itu, didapati bahwa ikatan 5-fold memberikan kontribusi paling besar dalam membentuk puncak sudut 60 o .

IOP Conference Series: Materials Science and Engineering

Germanene is a two-dimensional material which is derived from germanium elements and arranged in ... more Germanene is a two-dimensional material which is derived from germanium elements and arranged in a honeycomb-like hexagonal. This study aims to determine the optical properties of pristine germanene and effect of doping Sodium (Na) and Chlorine (Cl) atom on germanene. These elements are chosen owing to their ability to create strong bonds with germanene and easily available in nature. This research uses Density Functional Theory approach to measure the effects of sodium and chlorine doping on germanene's optical properties. The results showed that pristine germanene had higher optical and energy than the doped with sodium and chlorine. Cl-doped germanene had similar graphical shape with pristine germanene

Key Engineering Materials

Germanene, which has the same structure as graphene, is an exciting novel 2D functionalized mater... more Germanene, which has the same structure as graphene, is an exciting novel 2D functionalized material that controls its band gap using functionalization. The effects of the Ga atom and hydrogen atoms on the structure of Ga-doped H-passivated germanene were investigated with a density functional theory (DFT) calculation. H-passivated germanene has a direct gap of 2.10 eV. Opening the band gap in the H-passivated germanene is due to transition from sp2 to sp3 orbital. Adsorption of the Ga adatom on H-site decrease the band gap to 1.38 eV. No interaction between Ga atoms and Hydrogen atoms was observed. Hence, their effects on the band structure of hydrogenated graphene were independent of each other. Our results suggest that hydrogen passivation combined with adsorption of the Ga adatoms could effectively control the band gap of germanene.