Ex) Article Title, Author, Keywords
Abstract : Single-crystal hexagonal Si microneedles with an aspect ratio (length/diameter) of 195 or more were grown by using a mixed-source HVPE method at atmospheric pressure. The newly designed mixed-source HVPE method at atmospheric pressure generates a precursor gas with a high partial pressure due to the rapid reaction of Si and HCl gas at a high temperature of 1200 ◦C. At the same time, hexagonal Si microneedles are grown due to the formation of a nucleus and a seed caused by the interaction between GaCln, AlCln and SiCln gas, and it is designed as a growth mechanism that is separated from the substrate by free fall according to the grown weight. Scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), high-resolution X-ray diffraction (HR-XRD), and Raman spectra revealed a single crystal and pure hexagonal Si microneedle. As a result, the newly designed atmospheric pressure mixed-source HVPE method is expected to enable mass growth of single-crystal hexagonal Si microneedle.
Abstract : The purpose of this study was to investigate preservice physics teachers’ perceptions of self-understanding and change capacity related to science education. To this end, the responses of 308 students in a department of physics education at 11 universities were analyzed using a questionnaire. The questionnaire was designed to ask for the self-understanding and the change capacity related to science education. The results of the study were as follows. First, preservice physics teachers were positive in their perception of self-understanding as preservice teachers (average 3.81) and as preservice science teachers (average 3.78), the difference between them not being significant. Second, as for the change capacity, they were positive in the recognition of that as general (average 3.97), as preservice teachers (average 3.85), and as preservice science teachers (average 3.83) with significant differences in some factors. By and large, a gender difference was found. These results have great implications for improving preservice physics teachers’ professionalism and their identities as teachers.
Abstract : Pr3+-doped Y2O3 powders were synthesized using high-energy ball milling. Their structural and photoluminescence properties were investigated as functions of the concentration of the praseodymium and the annealing temperatures. The X-ray diffraction peaks of the Y2O3:Pr3+ powders matched the standard X-ray diffraction(XRD) peaks of the cubic Y2O3 phase without impurities well. The intensity of the XRD peak increased with increasing annealing temperature, as did the photoluminescence emission intensity. These results indicate that the crystallinity of the powder improved with increasng annealing temperature. The highest PL emission intensity was observed at an annealing temperature of 1200 ◦C and Pr3+ concentration of 0.1 mol%. The PL spectra showed characteristic peaks at 618 (3P0 → 3H6), 630 (2D1 → 3H4), 644 (3P0 → 3F2), and 509 nm (3P0 → 3H5) at an excitation wavelength of 285 nm.
Abstract : Carbon dots were synthesized using a solvothermal method with a HEPA filter/fine dust as carbon sources. The chemical structure, particle size, surface chemical ligand, electronic structure and luminescent characteristics of the carbon dots were analyzed using transmission electron microscopy. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and photoluminescence measurements, respectively. The photoluminescence spectrum of the carbon dots showed a strong cyan fluorescence around 452 nm under 370 nm excitation. Thus, high-efficiency carbon quantum dots using discarded fine dust can be developed, and the developed quantum carbon dots may be a good candidate for potential applications in the fields of LED color rendering improvement, fingerprint detection and anti-counterfeiting.
Abstract : In this research, we successfully fabricated a (trifluoromethanesulfonyl)-amide (TFSA)-doped graphene (TFSA-GR)/porous Si (PSi) solar cell by inserting a chemical vapor deposition-hexagonal boron nitride (h-BN) insulating layer. The photovoltaic parameters of the solar cell depent greatly on the presence or the absence of the h-BN insulating layer and TFSA-GR doping. Specifically, the h-BN insulating layer prevents carrier recombination at the TFSA-GR/PSi interface, thereby improving the charge collection/separation function and, consequently, improving the efficiency. As a result, the TFSA-GR/h-BN/PSi solar cells show a maximum PCE of 12.07%. These results demonstrate that h-BN is excellent as an insulating layer in GR/Si solar cells and is promising for use in graphene/Si-based optoelectronic device application.
Nguyen Ngoc DUY*, Latsamy XAYAVONG, Nguyen Kim UYEN, Vinh Nguyen Thanh PHAM, Tran Viet NHAM HAO
New Phys.: Sae Mulli 2019; 69(10): 1091-1100
Byeong-Hyeon JEONG, Ji-Sang PARK*
New Phys.: Sae Mulli 2020; 70(8): 630-636
Woo Tae Hong, Hyun Kyoung Yang
New Phys.: Sae Mulli 2021; 71(3): 236-241