Phan Thi Minh Man
Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, 70000, Vietnam

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Photoluminescence Broadening Induced by Internal Electric Field Variations in Polar InGaN/GaN Quantum Wells Nguyen Thi Phuong Loan; Phan Xuan Le; Phan Thi Minh Man
Indonesian Journal of Material Research Vol. 4 No. 3 (2026): Future Issue: November
Publisher : Magister Program of Material Science Graduate School of Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/ijmr.20264388

Abstract

This study investigates the influence of internal electric field modulation on photoluminescence (PL) broadening in polar InGaN/GaN quantum wells (QWs). By applying an external bias, the internal electric field is effectively controlled, allowing systematic evaluation of its role in spectral broadening. Photoluminescence and electro-reflectance measurements reveal that reducing the internal electric field leads to a noticeable narrowing of the PL linewidth. A theoretical model is developed to describe the relationship between electric field fluctuations and emission energy variation. The results indicate that stronger internal electric fields enhance the sensitivity of emission energy to local potential fluctuations, thereby increasing PL broadening. Additionally, a reduction in the Huang-Rhys factor is observed under decreased electric field conditions, suggesting weakened exciton-phonon coupling. These findings provide direct experimental evidence of the role of internal electric fields in PL broadening and offer a pathway for spectral control in III-nitride optoelectronic devices.
Structural and Optical Properties of Co-Doped ZnO Nanoparticles Synthesized by the Sol-Gel Method Nguyen Thi Phuong Loan; Lee Hsiao-Yi; Phan Thi Minh Man
Indonesian Journal of Material Research Vol. 4 No. 3 (2026): Future Issue: November
Publisher : Magister Program of Material Science Graduate School of Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/ijmr.20264395

Abstract

ZnO is recognized as a wide-bandgap semiconductor (3.37 eV) possessing a relatively huge exciton binding power (~60 meV), which makes it highly attractive for optoelectronic technologies. According to the current study, Co-incorporated ZnO nanoparticles were fabricated through an economical sol-gel synthesis route. The structural and optic characteristics were comprehensively underwent examination using XRD, SEM, and UV-Vis methods. Diffraction results reveal that all synthesized samples retain a pure hexagonal wurtzite phase, with no evidence of secondary phases, confirming effective Co incorporation into the ZnO lattice. As the Co concentration increases, a slight reduction in crystallite size is observed, indicating lattice distortion induced by dopant atoms. SEM analysis shows that the particles are predominantly quasi-spherical with minor agglomeration, and doping does not significantly alter their morphology. From an optical perspective, increasing Co content causes the absorption edge to shift toward longer wavelengths, accompanied by stronger absorption in the visible region. Bandgap values, extracted using Tauc analysis, reduce from 3.18 eV (undoped ZnO) to 2.94 eV at 3 mol% Co, followed by a marginal increase at higher concentrations. This trend is associated with the introduction of impurity-related electronic states within the bandgap. Overall, Co incorporation provides an effective means to modulate the optical response of ZnO nanostructures, thereby enhancing their suitability for advanced optoelectronic applications.
Non-Proximity as Well as Immediate Tracking for Phosphor Heat Within Phosphor-Transmuted WLED Apparatuses Nguyen Thi Phuong Loan; Phan Xuan Le; Phan Thi Minh Man
Indonesian Journal of Material Research Vol. 4 No. 2 (2026): July
Publisher : Magister Program of Material Science Graduate School of Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/ijmr.20264280

Abstract

Phosphor-transmuted white illuminating diode units (ptWLEDs) prove to be an essential illumination means for universal illumination. For balancing the photometrical attributes for ptWLED apparatuses, significant endeavors are still aiming at regulating the thermic abatement for LED colorants. The thermic issues for phosphor components, being a profound dependability trouble in ptWLED apparatuses, continue to be a significant subject for research. The study herein concerns a reliable method capable of assessing phosphor heat within functioning ptWLED via a non-proximity, immediate tracking technique for distantly tracking the discharge spectrum. Usually, infrared cameras or thermocouples would be employed for assessing heat. IR cameras need decent calibrating for discharge and would be typically obstructed via lenses or disparate modules covering phosphor samples. Furthermore, thermocouples need a period for achieving thermic anology among the tracker as well as samples subject to experiment. Said method would be detrimental if employed in intrinsic tracking. The method herein offers benefits surpassing ordinary techniques for non-intrusiveness, non-proximity, immediate as well as intrinsic tracking. Said technique would not be influenced by apex wavelength for pump illumination, the dosage as well as breadth for phosphors as well as correlated chroma heat (CCT).
Degeneration in Phosphor-within-Glass Encasers Featuring Disparate Phosphor forms Applied to High-Powered LED Phan Xuan Le; Nguyen Thi Phuong Loan; Phan Thi Minh Man
Indonesian Journal of Material Research Vol. 4 No. 2 (2026): July
Publisher : Magister Program of Material Science Graduate School of Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/ijmr.20264281

Abstract

For supplanting traditional illuminating diode units (LED) made of silicone, non-organic chroma transmuters featuring significant thermic consistency as well as translucency, including phosphor-within-glass (PWG), are examined in the form of encasers applied to high-powered LED apparatuses. The study herein concerns the influence from disparate phosphor forms featuring different chromas (LuAG, silicate, CASN as well as oxynitride) upon the dependability as well as degeneration for separate PWG encasers in the case of high-powered LED apparatuses. Regarding said goal, one glass constitution was individually blended into every phosphor form before undergoing a sintering process under proper heat levels, creating respective PWGs. The dependability in said PWGs underwent examination via conventional quickened aging experiments. Brightness penalties as well as variances for chroma coordinate results from the PWGs underwent assessment prior as well as posterior to aging. Thermic as well as dampness-generated abatement mechanism underwent assessment as well. The exterior for PWGs with disparate phosphor samples degenerated disparately, likely caused by formational inconsistencies among the glass latticework as well as phosphor form. As such, identifying the consistency for the glass constitution alongside the employed phosphor form proves paramount for guaranteeing prolonged consistencies for encasers applied to LED apparatuses in the market.