yusmar palapa wijaya

EDUCATION

M. M2 EsCO, Universite bretagne occidentale

RESEARCH, TEACHING, or OTHER INTERESTS

Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials

FUTURE PROJECTS

Scopus Publications

Plasma Power Effect to the Structure and Morphology of Strontium Stannate Thin Film
Yusmar Palapa Wijaya, Khairul Anuar Mohamad, Afishah Alias, Zulkifli Azman, Bablu Kumar Ghosh, and Abu Bakar Abd Rahman
Akademia Baru Publishing
Hybrid p-n heterojunction requires a suitable n-type material to support the charge transfer process in photodiode or solar cell applications. Numerous materials have been researched in terms of wet and dry processes. This paper investigated the effect of varied plasma power levels of 50 W, 80 W and 100 W at room temperature on the structure and morphology of an alkaline-earth-based perovskite oxide thin film. Strontium stannate (SrSnO3) thin films are deposited on an indium tin oxide (ITO) substrate using radio frequency (RF) magnetron sputtering at various power levels. The crystallographic orientation of the thin films was examined and it was observed that the (102) plane exhibited dense growth at low power, while the (002) plane showed increased intensity at higher power levels. Additionally, the increase in RF power resulted in larger crystallite and grain sizes, along with modified grain boundaries. Contrarily, surface roughness, resistivity, macrostrain and work adhesion were reduced. The nearly zero W-H linear fitting plot observed at 80 W can serve as a valuable reference for the fabrication of preferred films. These findings provide valuable insights for optimising the growth conditions of alkaline-earth-based perovskite oxide thin films for various applications.


Thickness and Resistivity Study of AlN Thin Film on Silicon Wafer Prepared by Reactive HiPIMS
Zulkifli Azman, Norain Sahari, Ahmad Shuhaimi Abu Bakar, Mohd Azwadi Omar, Ahmad Nasrull Mohamed, Yusmar Palapa Wijaya, Mohd Yazid Ahmad, and Nafarizal Nayan
IEEE
We explored the potential of the HiPIMS technique to deposit a uniform AlN thin film on a standard 2-inch Si wafer, emphasizing its future utility in manufacturing. The deposition process yielded an AlN thin film with consistent thickness, measuring 176.2 ± 2.4 nm, aligning with the uniform reflectance spectrum observed through ellipsometry analysis. The thickness was further substantiated by cross-sectional images obtained via FESEM. In terms of electrical properties, measurements from eight distinct wafer sections revealed an average resistivity of 2.29 Ohms.cm, with a calculated average sheet resistance of 1.14 x 105 Ohms/Sq. These results underscore the high electrical resistivity of the AlN thin film, while emphasizing its uniformity across the entire 2-inch wafer. These findings highlight the distinctive capabilities of the HiPIMS technique and its potential for producing uniform thin films.


Fabrication of Uniform Aluminium Nitrate Thin Film on 2-inch Silicon Substrate
Siti Ashraf Binti Abdullah, Nurul Syamimi Binti Abd Aziz, Mohamad Hafiz Mamat, Zulkifli Azman, Norain Sahari, Ahmad Nasrull Mohamed, Yusmar Palapa Wijaya, and Nafarizal Nayan
IEEE
Aluminium nitrate (AlN) has attracted numerous interests among researchers due to its unique properties in the semiconductor material and other high-performance devices. Investigating the uniformity of AlN thin film is one of the most challenge tasks. In this study, AlN thin films successfully deposited on a 2-inch of silicon substrate by using the magnetron sputtering technique. The uniformity analysis has been done by various characterization method such as XRD, AFM, surface profiler and FESEM. After depositing AlN thin film into 2-inch Si wafer, the thickness measure at 4 spot shows inconsistency and not reach expected uniformity, however the value at center d is the nearest to reach uniformity due to lowest value for average surface roughness, highest thickness value and acceptable value of crystallinity.


Achieving Compact Structure and Good Mechanical Properties of AlN Thin Film through Low Temperature HiPIMS
Zulkifli Azman, Nafarizal Nayan, Chin Fong Soon, Ahmad Shuhaimi Abu Bakar, Ahmad Nasrull Mohamed, Norain Sahari, Yusmar Palapa Wijaya, and Mohd Yazid Ahmad
IEEE
Thin films of aluminium nitride (AlN) were successfully deposited using the High Power Impulse Magnetron Sputtering (HiPIMS) technique at room temperature. X-ray diffraction (XRD) analysis confirmed a hexagonal close-packed (hcp) AlN crystal structure in the films. Notably, a highly pronounced orientation along the (002) plane was observed at the lowest sputtering pressure of 3 mTorr, while higher pressures led to the formation of a polycrystalline structure. The films deposited at 3 mTorr exhibited a dense and pebble-like morphology, resulting in impressive mechanical properties. The measured mechanical hardness was determined to be 17 GPa, and the Young's modulus was found to be 187 GPa. By reducing the sputtering pressure, the crystal quality, surface morphology, and mechanical properties of the films were observed to improve. This study demonstrates the potential of the HiPIMS technique to produce high-quality thin films at low temperatures, opening opportunities for various applications in fields such as electronics, optoelectronics, and materials science. The findings highlight the importance of process parameters in tailoring the properties of thin films for specific applications, paving the way for further advancements in thin film technology.


Morphological, structural and electrical properties of pentacene thin films grown via thermal evaporation technique
Fatin Nor Ahmad, Yusmar Palapa Wijaya, Khairul Anuar Mohamad, Nafarizal Nayan, Megat Muhammad Ikhsan Megat Hasnan, Afishah Alias, and Bablu Kumar Ghosh
Institute of Advanced Engineering and Science
The physical and structural characteristics of pentacene thin films on indium tin oxide (ITO)-coated glass were studied. The pentacene films were deposited using the thermal evaporation method with deposition times of 20, 30, and 60 minutes. Field-emission scanning electron microscopy (FESEM) images revealed that film thickness increased with deposition time, with a bulk phase layer appearing at 60 minutes. The presence of the thin-film phase corresponding to 15.5 Å lattice spacing was demonstrated by X-ray diffraction (XRD) patterns in pentacene films with deposition times of 20 and 30 minutes. Meanwhile, with a deposition time of 60 minutes and a lattice spacing of 14.5 Å, the existence of the bulk phase was verified in the pentacene film. Atomic force microscopy (AFM) images of the crystallinity of the pentacene films revealed that the pentacene films deposited on ITO-coated glass exhibited the formation of similar islands with modular grains, results in a fine crystalline structure. From the current-voltage (I-V) and current density-voltage (J-V) characteristics, the pentacene films were ohmic and that current increased as the pentacene’s thickness decreased. Pentacene films deposited on an ITO-coated glass substrate showed potential in the development of broadband and narrowband optoelectronic devices on a transparent substrate.


Pentacene Thin Film by Compact Thermal Evaporation System
Fatin Nor Ahmad, Khairul Anuar Mohamad, Yusmar Palapa Wijaya, Afishah Alias, Mohamad Syahmi Nordin, and Bablu Kumar Ghosh
IEEE
A compact thermal evaporation technique was used to fabricate pentacene thin films from a pure (99%) powder. All of the samples were grown at ambient temperature on glass substrates coated with indium tin oxide (ITO), and their optical, structural, and electrical properties were investigated. UV-visible (UV-Vis) spectroscopy and photoelectron spectroscopy in atmosphere (PESA) methods were used to evaluate the optical properties of a pentacene thin film utilising experimental values of optical band gap and ionisation potential. The energy band diagram of the highest occupied molecular orbital - lowest unoccupied molecular orbital (HOMO-LUMO) level depicts the electronic structure of pentacene. The HOMO and LUMO energy levels were determined toward being -5.49 eV and -3.74 eV, respectively, while the optical bandgap was 1.75 eV. Then, X-ray diffraction (XRD) was used to examine the structural properties of a thermally evaporated pentacene thin film. The XRD analysis revealed the bulk phase thin films oriented along the (001) plane direction. Finally, metal/pentacene/metal structured device was fabricated and showed a rectifying behavior.


Characterization and structural analysis of RF magnetron sputtered strontium stannate thin films
Yusmar Palapa Wijaya, Khairul Anuar Mohamad, Abu Bakar Abdul Rahman, Afishah Alias, and Mohammad Syahmi Nordin
Universitas Ahmad Dahlan
This paper presents physical and morphology properties of strontium stannate (SrSnO3) perovskite-type as a candidate of an n-type material thin film for organic-inorganic hybrid diode heterojunction for optoelectronics application. Typical wet-process of SrSnO3 deposition produce thick film and having 10-8 S/cm order in conductivity. The SrSnO3 thin films were deposited on ITO glass substrates by RF magnetron sputtering using a purity 99.9% SrSnO3 target with 5.0 mTorr of gas pressure and 100 W of RF power at room temperature. The gas composition of pure argon (75%) and reactive oxygen gas (25%) was used for 60 min. XRD diffraction patterns revealed that the thin films are orthorhombic crystal structure with lattice parameter a = 5.7040 Ǻ, b = 8.06 Ǻ and c = 5.7080 Ǻ with a strong orientation in the (002) direction. SEM images showed that films exhibited uniform surface morphology with a roughness average of Ra = 2.258 nm and thickness of 311 nm. The EDX spectrum confirmed the presence of O, Sr, and Sn elements in the films with 75.22%, 8.29%, 16.49% in atomic number, respectively. The films were having a conductivity of 8.33  102 S/cm with low resistivity of 12.4  10-3 -cm.


The Design of Wheelchair Systems with Raspberry Pi 3-Based Joystick Analog and Voice Control
Putri Madona, Husna Khairun Nisa, Yusmar Palapa Wijaya, and Amnur Akhyan
IOP Publishing
Abstract In this study, an electric wheelchair that combines two controls: joystick analog and voice control is designed. IC MCP3008 is used to navigate wheelchairs by using Josytick, where joystick analog data will be converted into digital data. The movements resulted from the joystick analog on the xAxis axis (horizontally) are the right turn and left turn, and on the yAxis axis (vertically) are forward and backward. The movements on the yAxis and xAxis axes set by the user affects the speed of the wheelchair. Meanwhile, the AMR-Voice application on Android is used to navigate wheelchairs by using sound. There are five commands in this voice control: “Forward”, “backward”, “left”, “right”, “stop”. The order will be sent to Raspberry Pi 3 via the HC-06 module to then be recognized for the command. If the voice commands are received accordingly, Raspberry Pi 3 will provide an activation signal to the motor driver to move the wheelchair in the direction corresponding to the command given by the user. Voice control testing on wheelchairs is tested in quiet rooms and noisy rooms. The results of the wheelchair control testing with sound indicate that the accuracy and speed of the wheelchair response rely heavily on Internet connection and room conditions. The average response when the condition of the room is quiet is 0.16 s and when the condition of the room is noisy is 5.18 s. Wheelchairs with joystick control and the voice made can be used for the disabled, whether for those who can move their fingers or not, at a low cost so that they can be an alternative in developing countries.


Controlling the Direction of Wheelchair Movement Using Raspberry-Pi Based Brain Signals
Putri Madona, Renndy Raldy Mujiono, and Yusmar Palapa Wijaya
IEEE
This study discusses the processing of EEG and EOG signals for the classification of wheelchairs movement. Brain signals are obtained with NeuroSky mind wave sensor; this sensor emits attention, meditation, and RAW data values. Attention value will be used for forward movement, meditation is used for backward movement, while RAW data will be used for left, right, and stop movements. The test results of forward orders have a success rate of 92%, turn right 96%, turn left 100%, stop 96%, and backward 76%.


Solar panel performance monitoring system in sensor node
Retno Tri Wahyuni and Yusmar Palapa Wijaya
IEEE
In Wireless Sensor Network (WSN) system, a power supply capable of harvesting energy independently is a very crucial component considering WSN commonly installed in a remote area far from the utility grid. The development of effective and efficient power supply is still ongoing because sensor node works continuously in real-time. The quantity of sensor node is also the reason why its power supply must be as effective and efficient as possible, thus relatively lower its cost. This paper discusses a system to monitor the performance of photovoltaic power supply from sensor node in a WSN system. The observed parameters are temperature, irradiance, current, and voltage. The system divided into 3 main blocks which are, client, server, and communication system. The client has sensors, RTC, local display, backup data logger, and microcontroller. The communication devices are radio-frequency module, Xbee. The server is a PC software developed using LabView software.