Suwat Sopitpan - Academia.edu (original) (raw)

Papers by Suwat Sopitpan

2022 IEEE International Conference on Consumer Electronics-Asia (ICCE-Asia), Oct 26, 2022

Social Science Research Network, 2022

2022 IEEE International Conference on Consumer Electronics-Asia (ICCE-Asia)

SPIE Proceedings, 2014

Inkjet printing of photoresist material may provide a new route for low-cost fabrication of patte... more Inkjet printing of photoresist material may provide a new route for low-cost fabrication of patterned oxide passivation layer of solar cells that require fine patterning and simple process. However, printing by liquid-based, environmentally friendly ink and printing device required development efforts aimed at achieving a fine patterning and long used inkjet nozzles under corrosive influence. This work was demonstrated a concept for grooved silicon oxide patterning for rear localized contact of p-n junction solar cells by chemical etching after photoresist patterning obtained. This article reviews the silicon dioxide fabrication on p-Si substrate from sol-gel technique for oxide passivation layer of solar cells. The aluminium was deposited on the patterned oxide layer and then heated at its Al-Si eutectic temperature. Finally, an aluminium-induced solid-phase epitaxial growth of p+ forming into the openings of the oxide passivation layer was presented. The sheet resistance of n-emitter layer, carrier life-time and surface recombination velocity values are investigated. Photoconductive measurements were performed on the prepared samples after each thermal process to measure the effective lifetime of the minority carriers. Carrier lifetime up to 60 microseconds has been measured on c-Si wafer passivated by the opened SiO2 layer. It was shown that the patterned SiO2 passivation has obtained high passivation quality making by the proposed inkjet printing method.

1999 ISES Solar World Congress, 2000

Materials Science and Engineering: B

Physica Status Solidi (a), 2019

Tuning growth of nanostructures can provide additional routes to engineer their characteristics. ... more Tuning growth of nanostructures can provide additional routes to engineer their characteristics. In this work, the authors report on a combined growth of GaSb/GaAs quantum dots (QDs) and growth of GaAs on (001) Ge substrate. Surface decorated with GaAs anti‐phase domain is the initial template to investigate the growth‐rate effects on the growth of self‐assembled GaSb QDs. By varying the GaSb growth rates, QD ensembles with different morphologies are formed. Perpendicular alignment of elongated GaSb QDs is observed. Cross‐sectional transmission electron microscopic images show a substantial reduction of lateral QD size when it is buried in GaAs matrix. Raman scattering as well as power‐dependent photoluminescence spectroscopies are performed to reveal the optical properties of the nanostructures. Type‐II band alignment characteristic is confirmed.

physica status solidi (a), 2018

We report the growth and photoluminescence (PL) properties of InSb/GaSb nano-stripes grown by mol... more We report the growth and photoluminescence (PL) properties of InSb/GaSb nano-stripes grown by molecular beam epitaxy on (001) GaSb substrate. In situ reflection high-energy electron diffraction observation during InSb growth shows that the growth of InSb on GaSb surface is in Stranski-Krastanov mode and results in nano-stripe formation. The obtained nano-stripes have rectangular-based with the height of 25.2±4.0 nm and they are elongated along [110] direction. PL emission from buried InSb/GaSb nano-stripes shows the emission peak at ~1850 nm (0.67 eV). According to the emission energy and the structural information, low In content of ~0.24 in nominally grown InSb/GaSb nano-stripe is estimated. Powerdependent PL spectroscopy shows a linear relation between integrated PL intensity and the excitation power. and the laser power without any signature of intensity saturation. Thermal activation energy of ~20 meV from InSb nano-stripe emission is extracted from the temperature-dependent PL spectroscopy.

2020 IEEE 2nd Global Conference on Life Sciences and Technologies (LifeTech), 2020

Currently, there are many numbers of patients with knee osteoarthritis (KOA) which is the most co... more Currently, there are many numbers of patients with knee osteoarthritis (KOA) which is the most common joint pain of osteoarthritis (OA). Joint stiffness and pain in the knee are the KOA symptoms depending on many causes. There are 13% of women, 10% of 60 years and older than 70 years men, the prevalence rises to 40%. Males are prevalent lower than in females [9]. This makes the number of doctors and medical assistance who specialize in monitoring the treatment inadequate for patients’ proportion. In addition, problems in patients’ accommodation are the long-distance travel, rural area, insecure route issue, e.g., in southern of Thailand, transportation, and requesting a helper or caregivers accompany to see a doctor every period. Therefore, this research approaches Internet of Things (IoT) technology with physical stabilization knee support as electronic medical records (EMR) on a website monitoring the KOA patients’ treatment results. The direct benefit is to increase the accuracy of the remote measurement, to analysis of symptoms and to facilitate the follow-up of medical treatment and improve the quality of rural patients’ life.

Journal of Crystal Growth, 2019

Interdigitated quantum dots, which are multiple stacks of type-I InAs/GaAs quantum dots and type-... more Interdigitated quantum dots, which are multiple stacks of type-I InAs/GaAs quantum dots and type-II GaSb/GaAs quantum dots, are grown using molecular beam epitaxy. By incorporating the interdigitated quantum dots into a p-in AlGaAs/GaAs heterojunction solar cell structure, we demonstrate a photovoltaic effect with a 20.6% improvement in open-circuit voltage, when compared to that of another cell incorporating the same quantum dots but with a p-in GaAs homojunction architecture. A transmission electron microscopy is performed to analyze strain-induced defects created in the multi-stack quantum dot structures. The heterojunction solar cell incorporating the interdigitated quantum dots realized in this work would find potential applications in highefficiency single-junction intermediate band solar cells operating under concentrated sunlight.

MRS Advances, 2015

ABSTRACTGaSb/GaAs and InSb/GaAs material systems can create type-II quantum nanostructures which ... more ABSTRACTGaSb/GaAs and InSb/GaAs material systems can create type-II quantum nanostructures which provide interesting electronic and optical properties such as having long carrier life time, low carriers-recombination rate, and emitting/absorbing low photon energy. These characteristics of type-II nanostructures can be applied for infrared or gas detection devices, for memory devices and even for novel intermediate band solar cells. In contrast, lattice mismatches of GaSb/GaAs and InSb/GaAs material system are 7.8% and 14.6%, respectively, which need some specific molecular beam epitaxial (MBE) growth conditions for quantum nanostructure formation via Stranski–Krastanov growth mode.In this paper, the growth of self-assembled GaSb and InSb quantum nanostructures on (001) GaAs substrate by using MBE was reported. The surface morphology of these two quantum nanostructures and their optical properties were characterized by atomic force microscopy and photoluminescence (PL). The experimen...

Solar Energy Materials and Solar Cells, 2001

ABSTRACT Monitoring of a PV system connected to a grid was conducted to collect the system perfor... more ABSTRACT Monitoring of a PV system connected to a grid was conducted to collect the system performance and compared to a PV stand-alone system. Daily solar inputs and load outputs for home applications of the two systems were recorded. Balance and surplus of energy in the systems were observed during dry and summer seasons when high solar radiation was recorded. During the raining season, with thunderstorms, solar radiation was low and grid cut-off occasionally occurred. Consequently, energy deficiencies and grid back-up of the systems were observed. It was found that the battery size of the PV system connected to the grid was reduced by a factor of 0.5–0.7 compared to the PV stand-alone counterpart for similar load behaviors. The merits of the PV system connected to the grid during grid cut-off was confirmed; the system proved to be appropriate for tropical countries where unstable electricity supply from the grid can occur during monsoon season.

2008 5th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2008

ABSTRACT This paper describes the impact of thickness of cobalt silicide to the sentivity of p-n ... more ABSTRACT This paper describes the impact of thickness of cobalt silicide to the sentivity of p-n junction temperature sensor. The starting cobalt thickness of 12, 20 and 30 nm and non-silicided reference wafer have been used. The maximum sentivity for starting cobalt thickness of 12 nm has been obtained from both large area and long perimeter p-n junction. This corresponds to the low leakage current and series resistance.

Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036)

Three different configurations of PV systems, i.e. PV stand-alone, PV direct and PV connected to ... more Three different configurations of PV systems, i.e. PV stand-alone, PV direct and PV connected to a grid, were set up and studied at a house in Bangkok. The results were compared to the grid-connected PV systems at other pilot project houses installed by the Electricity Generating Authority of Thailand. The three systems w e r e f o u n d t o o u t p e r f o r m t h e c o n v e n t i o n a l grid-connected PV system in many aspects.

Operation lifetime of the X-ray detector is the major factor that defines cost of detector or the... more Operation lifetime of the X-ray detector is the major factor that defines cost of detector or the actual operation cost of the detector. The purpose of this paper is to study the possibility of operation lifetime extension of the silicon x-ray detector. The study of the device's carrier generation lifetime before and after device exposed to the X-ray for 4 and 150 second at 40, 55 as well as 70 keV were conducted in this paper. The 1 mm2 p-n junctions were fabricated by boron implantation process into phosphorus doped silicon wafer. A commercial x-ray source for dentist was used to generate x-ray in these experiments. The carrier generation lifetime was calculated from current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The results show that the carrier generation lifetime increased after 4 second of x-ray irradiation at all three energy conditions but decreased back close to the original value after continue exposed devices for another 150 second. However, the ...

An investigation of morphology on titanium nitride (TiN) film has been presented in this study. T... more An investigation of morphology on titanium nitride (TiN) film has been presented in this study. TiN films were deposited on SiO 2 /Si(100) substrates by DC-magnetron sputtering from a Ti metal target using a mixture of nitrogen (N 2) and argon (Ar) gases. The flow rate ratios of the N 2 :Ar were performed as pure-N 2 , 3:1, 1:1 and 1:3 respectively. The sputtered time was fixed at 300 second. After deposition, these films were annealed in the N 2 ambient at temperature 420 °C and 500 °C. The morphology, crystalline orientation and composition of deposited TiN films were characterized by FE-SEM, XRD and AES respectively. The crystallization, morphology and composition of TiN films were examined as a function of annealing temperature and the flow rate ratios of the N 2 and Ar mixtures. Background Nitride compounds of titanium (TiNx) are unique materials exhibiting both metallic (Ti–Ti) and covalent (Ti–N) bonding characteristics. The metallic properties are electrical conductivity and...

2010 3rd International Nanoelectronics Conference (INEC), 2010

ABSTRACT Indium oxynitride (InON) thin films prepared by reactive gas-timing RF magnetron sputter... more ABSTRACT Indium oxynitride (InON) thin films prepared by reactive gas-timing RF magnetron sputtering technique are investigated using X-ray absorption fine structure and first principle calculation. It was found from the former study that optical and electrical properties of these films highly depended on its gas-timing ratio in the sputtering process. Therefore structural investigations of these films are required in order to describe the relation between the gas-timing ratio and their optical properties. The results show that local structure of the InON thin films consist of both indium oxide (In2O3) and indium nitride (InN) phase.

Key Engineering Materials, 2013

Formation of nano-crystalline p+ silicon (Si) in pinholes through a silicon dioxide layer was ach... more Formation of nano-crystalline p+ silicon (Si) in pinholes through a silicon dioxide layer was achieved by pinning of aluminum through the thin silicon dioxide (SiO2) layer. In addition to opening holes of SiO2 layer by aluminum (Al) pining, amorphous silicon (a-Si) was subsequent deposited on the Al layer and another heated at low temperature (500°C) to allow solid- phase epitaxial growth of p+ Si in the pinholes due to the Al induced layer exchange process. The poly-crystalline p+ Si obtains lower effective surface recombination than the Al back surface field (BSF). The technique demonstrated to result in ohmic contacts with low contact resistance. The evaluation of Al-induced crystallization of a-Si in a-Si/Al bilayer was studied by X-ray diffraction. In this paper, the influence of a-Si/Al thickness ratio on the specific conductivity value and crystalline grain size of the p+ Si thin film is discussed. The obtained results are helpful for a further design of the rear passivation ...

GaAs/AlGaAs and InGaAs/GaAs multquantum well (MQW) structures were fabricated by Molecular Beam E... more GaAs/AlGaAs and InGaAs/GaAs multquantum well (MQW) structures were fabricated by Molecular Beam Epitaxy (MBE) technique. Spectral response of these two quantum structures were investigated by photocurrent measurements. The response peak of the GaAs/ AlGaAs MQW is at 684 om and InGaAs/GaAs MQW exhibits responses maxima in 700-800 om spectral regions. The absorption of these two MQW structures depend on their multiplication of the same quantum well width.