pISSN 0374-4914 eISSN 2289-0041
• ### Research Paper 2020-12-31

#### Pixel Design Study of a CMOS Monolithic Active Pixel Sensor for the Charge Collection time

Sanghyeon LEE, In-Kwon YOO*

Abstract : A new silicon chip (INVESTIGATOR) manufactured for R\&D purposes has 134 mini-matrices with various pixel designs. Each matrix consists of 8 $\times$ 8 pixels, which put out 64 analogue signals at 65 MHz. The silicon pixel design is based on the newest technology of the complementary metal-oxide-semiconductor (CMOS) monolithic active pixel sensor (MAPS), which integrates the silicon sensor and the read-out circuitry in a pixel. The MAPS has advantages of low power consumption, high granularity of a pixel, and fast read-out. In this paper, the charge collection time for different pixel designs and reverse bias voltages is studied by using the INVESTIGATOR. The charge collection time is estimated by fitting the waveform for changing pixel pitch, reverse bias voltage, diameter of collection n-well diode, and spacing. Based on these results, we discuss the dependence of the relative depletion volume and the charge collection time on the pixel geometry.

• ### Research Paper 2020-12-31

#### $\alpha$ + $^{116}$Sn and $^{6}$Li + $^{116}$Sn Elastic Scatterings at $E_{lab}=$ 240 MeV  :  Coulomb-modified Glauber Model Approach

Yong Joo KIM*

Abstract : We analyzed experimental data on elastic $\alpha$ + $^{116}$Sn and $^{6}$Li + $^{116}$Sn scatterings at $E_{lab}=$ 240 MeV within the framework of the Coulomb-modified Glauber model. The ingredients of the model used in this work were the nucleon-nucleon ($NN)$ amplitude and the densities of the colliding nuclei. The calculations included the effective $NN$ amplitude considering a $q^{4}$ component and the surface-matched Gaussian density of the target nucleus. The calculated results reproduced satisfactorily the structures of differential cross sections and agreed well with the experimental data. \ The oscillatory structures observed in the angular distributions were explained using the strong interference between the near-side and the far-side scattering amplitudes. We found that the introduction of both an effective $NN$ amplitude and a surface-matched Gaussian density plays an important role in providing a better description of the elastic data.

• ### Research Paper 2020-11-30

#### Effects of Partial Substitution of Nitrate on the Superconducting Properties of TlSr$_{4}$Cu$_{2}$O$_{z}$(SO$_{4}$)

Ho Keun LEE*

Abstract : The effects of partial substitution of nitrate groups at the SO$_{4}$ sites on the superconducting properties of the TlSr$_{4}$Cu$_{2}$O$_{z}$(SO$_{4}$)$_{1-x}$(NO$_{3}$)$_{x}$ system have been investigated. X-ray diffraction data showed that the solubility limit of (NO$_{3}$) was about $x$ = 0.35. The change in the solubility limit of oxyanion for sulfate was discussed in connection with the characteristics of the oxyanion species. Within the solubility limit, the introduction of the nitrate groups did not change significantly the transition temperature of the pristine TlSr$_{4}$Cu$_{2}$O$_{z}$(SO$_{4}$) compound. However, we found that compared to the pristine compound, the introduction of the nitrate groups degraded the stability properties of the sample after annealing at 400$^{\circ}$C in Ar atmosphere.

• ### Research Paper 2020-11-30

#### Fabrication of Epitaxial Cu$_{2}$O (111) Films from Cu(111) thin Films by Rapid Thermal Oxidation

Miyeon CHEON, Yousil LEE, Sujae KIM et al.

Abstract : Due to the energy gaps of copper from 2.1 to 2.7 eV, its high light absorption, its nontoxicity and its abundance on the earth, Cu$_{2}$O is an attractive material for use in various areas such as photovoltaic power generation, photocatalytic reactions, water photolysis, nonlinear optics, and gas sensing. Many researches efforts are being conducted to obtain high-quality Cu$_{2}$O thin films. In this study, high-quality, epitaxial Cu$_{2}$O (111) thin films were obtained via a relatively simple method, rapid thermal processes at high temperature of RF sputtered Cu (111) thin film on a sapphire substrate. XRD, SEM and UV-Vis spectroscopy measurements confirmed the high crystallinity of the Cu$_{2}$O (111) thin film oxidized for 30 minutes at a temperature of 800 $^{\circ}$C under an atmosphere of argon with 3 ppm of oxygen. Also, because of the high crystal-quality of the Cu$_{2}$O (111) thin films, blue and indigo energy gaps at room temperature were obtained from the absorption coefficient $\alpha$. The obtained energy band gaps are consistent with the theoretical values obtained from Cu$_{2}$O bulk structures.

• ### Research Paper 2020-10-30

#### Far-infrared spectroscopic study on MAPbI$_3$ and MAPbBr$_3$

Jaeseung LIM, Sangheon PARK, Yu-Seong SEO et al.

Abstract : MAPbX$_3$, is an organic-inorganic perovskite material system which can be applied in various areas such as magneto-optical data storage, solar cells, lasers, LEDs, etc. MAPbI$_3$ and MAPbBr$_3$ are known to undergo a cubic-to-tetragonal transition at temperatures of about 327 K and 220 K and a tetragonal-to-orthorhombic transition at about 150 K and 145 K, respectively. The transmittance spectra of pallet samples are measured in the far-infrared (FIR) region at various temperatures from room temperature to 80 K by using a Fourier transform infrared (FTIR) spectroscopy-type Bruker Vertex 80v spectrometer. The absorption coefficients are obtained and fitted by using the Drude-Lorentz model to obtain other optical constants including the electric permittivity, optical conductivity, and extinction coefficient. Then, the optical conductivity is fitted to obtain the position and damping coefficient of the longitudinal optical (LO) and the transverse optical (TO) phonons for the sample materials, which are used to calculate the electron-phonon coupling constants, polaron mass, and polaron radii.

## Current Issue

December, 2020 | Volume 70, No. 12
• ### Research Paper 2020-12-31

#### First-principles Study of Intrinsic Stability of Perovskite Halide MAPbI$_{3}$

Dokyun KIM, Chul Hong PARK*

Abstract : We examined the stability of the MAPbI$_{3}$ perovskite through a first-principles total energy calculation and estimated the thermodynamic energy through phonon calculations. The total energies calculated for the ground state showed that the energy for the dissociation of MAPbI$_{3}$ into MAI and PbI$_{2}$ is small relative to the thermal energy at room temperature, indicating that MAPbI$_{3}$ is not stable for dissociation. We estimated the dependence of the thermodynamics free energies of MAPbI$_{3}$ and MAI and PbI$_{2}$ on the temperature. We found that the entropy effect can contribute to the stabilization of MAPbI$_{3}$, however the stability is not so robust. Because the PbI$_{2}$ has a two-dimensional layered structure, the entropy effect is small compared to that of the three-dimensional structure.

• ### Research Paper 2020-12-31

#### Research on Microstrip Transmission Line Design for Microwave Memristive Devices

Hanju LEE*

Abstract : We conducted research on the microwave memristive response of a microstrip transmission line (MTL) coupled with an yttrium iron garnet (YIG) thin film. We investigated the memristive responses of YIG-MTL devices with MTL signal lines of different widths. Measurement results showed that a decrease in the width of the MTL signal line resulted in an improvement of the microwave memristive response of the YIG-MTL device. Based on transmission line theory, we showed that the enhancement of the memristive property of the MTL was due to an increase in the inductance that was caused by a decrease in the width of the signal line. The increase in the inductance of the MTL caused an increase in the strength of the microwave magnetic near field, and as a result, the magnetic coupling between the YIG and MTL was improved. The present result provides a useful way to improve the memristive response of a wave memristive device and should be helpful in the design of wave memristive microwave device.

• ### Research Paper 2020-12-31

#### Up- and down-conversion Luminescence Characteristics of (Gd$_{0.85-x}$Yb$_{0.15}$)AlO$_{3}$:Er$_{x}^{3+}$ Phosphors

Kang Hyun KIM, Soung Soo YI*

Abstract : Er$^{3+}$and Yb$^{3+}$ co-doped Gd$_{(0.85-x)}$AlO$_{3}$:Yb$_{0.15}^{3+}$, Er$_{x}^{3+}$ ($x$ = 0.06, 0.09, 0.12 and 0.15) polycrystalline powders have been prepared by using a solid-state reaction method. The crystallinity of the powders shows a polycrystalline orthorhombic system. For the down-conversion photoluminescence, through the direct excitation of Er$^{3+}$ ions using a wide emission spectrum in the range of 420 ~ 500 nm from the host crystal and 520 ~ 570 nm from the Er$^{3+}$ ions has been observed. The up-conversion photoluminescence properties of Gd$_{(0.85-x)}$AlO$_{3}$:Yb$_{0.15}^{3+}$, Er$_{x}^{3+}$ phosphors were investigated in detail. The green and the red up-conversion emissions from the phosphors were observed under an excitation at 980 nm by using a semiconductor laser. The powders exhibited strong green and weak red up-conversion emission peaks at 545 and 657 nm, respectively. The luminescence intensity showed the different Er$^{3+}$ concentration dependencies for the up- and down-conversion luminescence behaviors due to the difference in their luminescence mechanisms. The maximum intensities for the up- and down-conversion luminescence occurred at Er$^{3+}$ ions 0.12 and 0.09 mol, respectively.

• ### Research Paper 2020-12-31

#### Microwave Synthesis and Luminescent Properties of red Emitting Ca$_{3}$ZrSi$_{2}$O$_{9}$:Eu$^{3+}$ Phosphor for Latent Fingerprint Detection

Woo Tae HONG, Hyun Kyoung YANG, Byung Kee MOON*

Abstract : Ca$_{3}$ZrSi$_{2}$O$_{9}$:Eu$^{3+}$ (CZS:Eu$^{3+}$) phosphors were synthesized by using a microwave irradiation method. The crystal structure, surface morphology and luminescence properties of the phosphors were analyzed for different Eu$^{3+}$ concentrations. The CZS:Eu$^{3+}$ phosphor exhibited their strongest emission at 610 nm under 392-nm excitation. Because the CZS:Eu$^{3+}$ phosphor contains 7 mol% of Eu$^{3+}$, the luminescent intensity at the dominant emission wavelength was maximized. Considering these analysis we applied, the CZS:Eu$^{3+}$ phosphors to detect latent fingerprints on various substrate materials. Under UV excitation, the detected fingerprints showed a red emission with high resolution. The results of this study show that the CZS:Eu$^{3+}$ phosphor can be used as luminescent sensor to detect latent fingerprints.

• ### Research Paper 2020-12-31

#### Synthesis and Characterization of Mn-doped CdSe Quantum dots

Eun-Bee JUNG*, Il-Gon KIM, Dong-Sun YOO

Abstract : We fabricated Mn-doped CdSe QDs by mixing Mn-acetate (Mn(CH$_{3}$CO$_{2}$)4H$_{2}$O) with 0.5 mmol of cadmium oxide (CdO) in the stage of Cd$^{2+}$ precursor synthesis and investigated the effects of Mn doping. When the amount of Mn-acetate mixed was below 0.1 mmol, the properties of QDs doped like PL spectra and the XRD patterns, were not different from those of undoped QDs, and this resulted from the difference in reaction rates for Cd-Mn and Mn-oleate formation. On the other hand, when the amount of Mn-acetate mixed reached 0.5 mmol, the XRD patterns and the PL spectra showed that the doped QDs had a core-shell structure a CdSe core with a big band gap energy and a MnSe shell with small band gap energy, and in this core-shell structure, the surface passivation ligands changed from Cd-oleate of CdSe to Mn-oleate of MnSe.

• ### Research Paper 2020-12-31

#### Pixel Design Study of a CMOS Monolithic Active Pixel Sensor for the Charge Collection time

Sanghyeon LEE, In-Kwon YOO*

Abstract : A new silicon chip (INVESTIGATOR) manufactured for R\&D purposes has 134 mini-matrices with various pixel designs. Each matrix consists of 8 $\times$ 8 pixels, which put out 64 analogue signals at 65 MHz. The silicon pixel design is based on the newest technology of the complementary metal-oxide-semiconductor (CMOS) monolithic active pixel sensor (MAPS), which integrates the silicon sensor and the read-out circuitry in a pixel. The MAPS has advantages of low power consumption, high granularity of a pixel, and fast read-out. In this paper, the charge collection time for different pixel designs and reverse bias voltages is studied by using the INVESTIGATOR. The charge collection time is estimated by fitting the waveform for changing pixel pitch, reverse bias voltage, diameter of collection n-well diode, and spacing. Based on these results, we discuss the dependence of the relative depletion volume and the charge collection time on the pixel geometry.

• ### Research Paper 2020-12-31

#### Growth Probability of an Additional Offspring with a Beneficial Reversal Allele in the Four-State Haploid Coupled Discrete-Time Mutation-Selection Model for a Finite Population

Wonpyong GILL*

Abstract : Growth probabilities of an additional offspring with a beneficial reversal allele were calculated by computer simulation for various population sizes, sequence lengths, selective advantages, and measuring parameters for a finite population in the four-state haploid coupled discrete-time mutation-selection (HCDMS) model. The mutation rates between all sequence elements were set to be equal. This study suggested that the boundary between the deterministic and the stochastic regions in the four-state HCDMS model could be determined by using the same criterion as that in the two-state HCDMS model. For various population sizes, sequence lengths, measuring parameters, and selective advantages, the growth probabilities in the stochastic region could be described using the theoretical formula for the growth probability in the Wright-Fisher two-allele model.

• ### Research Paper 2020-12-31

#### Mesoscale Properties of Mutualistic Networks in Ecosystems

Sang Hoon LEE*

Abstract : Uncovering the structural properties of ecological networks is a crucial starting point when studying the system's stability in response to various types of perturbations. We analyze pollination and seed disposal networks, which are representative examples of mutualistic networks in ecosystems, in various scales. In particular, we examine mesoscale properties such as the nested structure, the core-periphery structure, and the community structure by statistically investigating their interrelationships with real network data. As a result of community detection on different scales, we find an absence of a meaningful hierarchy between networks, and a negative correlation between the modularity and the two other structures (nestedness and core-periphery-ness), which themselves are highly positively correlated. In addition, no characteristic scale for the communities is perceivable from the community-inconsistency analysis. Therefore, community structures, which are the most widely studied mesoscale structures of networks, are not, in fact, adequate to characterize mutualistic networks of this scale in ecosystems.

• ### Research Paper 2020-12-31

#### $\alpha$ + $^{116}$Sn and $^{6}$Li + $^{116}$Sn Elastic Scatterings at $E_{lab}=$ 240 MeV  :  Coulomb-modified Glauber Model Approach

Yong Joo KIM*

Abstract : We analyzed experimental data on elastic $\alpha$ + $^{116}$Sn and $^{6}$Li + $^{116}$Sn scatterings at $E_{lab}=$ 240 MeV within the framework of the Coulomb-modified Glauber model. The ingredients of the model used in this work were the nucleon-nucleon ($NN)$ amplitude and the densities of the colliding nuclei. The calculations included the effective $NN$ amplitude considering a $q^{4}$ component and the surface-matched Gaussian density of the target nucleus. The calculated results reproduced satisfactorily the structures of differential cross sections and agreed well with the experimental data. \ The oscillatory structures observed in the angular distributions were explained using the strong interference between the near-side and the far-side scattering amplitudes. We found that the introduction of both an effective $NN$ amplitude and a surface-matched Gaussian density plays an important role in providing a better description of the elastic data.

• ### Research Paper 2020-12-31

#### Content Analysis of Interference and Diffraction Presented in High School Physics Textbooks

Bongwoo LEE*

Abstract : The purpose of this study is to analyze the explanation of interference and diffraction presented in high school physics textbooks. The definitions and the principles of interference and diffraction, as well as examples of interference and diffraction, in 13 physics textbooks according to the 2015 revised curriculum were analyzed. The definitions of interference were similarly described for each textbooks, but inaccurate expressions were found in the section describing coherence and constructive/destructive interference as a phase. Regarding diffraction, the degree of explanation of Huygen’s principle differed among textbooks, and some textbooks used the concept of 'interference' in the process of explaining the principle of diffraction. Examples of interference and diffraction have been described in various examples, but the same phenomena have been explained by using different principles (interference, diffraction) depending on the textbook. Based on the results, we discuss the unnecessariness of the dichotomy of interference and diffraction, as well as the teaching method for interference and diffraction.

• ### Research Paper 2020-12-31

#### Comparison of Characteristics of Research Paper Introduction by Research Types in Physics Education

Kwanghee JO*

Abstract : This study attempted to examine the similarities and differences in the research paper introduction description of Korean physics education according to the research type. To this end, we reviewed physics education papers recently published in the journal “New Physics: Sae Mull,” and selected research papers corresponding to three representative types. The number of sentences constituting the introduction part was the lowest in experiment development studies and the highest in conception survey studies among the three types. According to the genre analysis results, the arrangement of the steps or the ratio of moves in the introduction description for each research type was different. In the experiment development study, the step of presentation of current situation occupied the greatest ration in the introduction, and relatively more sentences were used to derive the research necessity. Textbook analysis studies tended to focus on the obligatory steps of introduction. Overall, there was relatively little variation was seen among the papers belonging to this type. An average of more than 20 sentences was allocated to the presentation of previous research and the specification the research topic in the conception survey study. Through this study, some of the characteristics of a research paper introduction were found to differ depending on the research types.

• ### 2020-12-31

#### Landau States in Time-Dependent Magnetic Fields

Won KIM, Sang Pyo KIM*

Abstract : We present the oscillator representation of the Pauli Hamiltonian for a scalar charge in a magnetic field and find a basis that diagonalizes the Hamiltonian in the special case of a constant or slowly varying magnetic field. We show that the diagonalization of the new basis is a canonical transformation in phase space, which leads to the Pauli Hamiltonian and counts the degeneracy of the Landau levels. Finally, we obtain the Liouville-von Neumann equation for quantum invariants as the annihilation and the creation operators for a scalar charge in time-dependent magnetic fields.

• ### Research Paper 2020-12-31

#### Twist-angle Dependence of the Ground Exciton Energy in Twisted Bilayer MoS$_2$

Junkyoung KIM, Haeun CHA, Inwoo PARK et al.

Abstract : The exciton is an electron hole bound state in semiconductors and plays an important role in opto-electronic devices such as light-emitting diode. Therefore, a desire exists to control the exciton formation energy, which is closely related to characteristics of optoelectronic applications. Here, we report formation energy of ground exciton states in a MoS$_2$ twisted bilayer measured by using photoluminescence spectroscopy. By varying the twist angle, we found that the exciton formation energy was tunable within the energy range roughly between 1.87 eV at about 0$^{\circ}$ and 60$^{\circ}$ twist angles and 1.90 eV at about a 30$^{\circ}$ twist angle. The exciton formation energy is directly related to the band gap energy, and the band gap of a bilayer MoS$_2$ becomes smaller than that of a MoS$_2$ monolayer due to interlayer coupling. Our results can be explained by the fact that the interlayer distance is smaller and the interlayer coupling is larger at 0$^{\circ}$ and 60$^{\circ}$ twist angles than at 30$^{\circ}$ twist angle. The twist angle dependence of the exciton formation energy can also be qualitatively explained by the twist-angle-dependent direct band-gap energy from first-principles calculations results.

• ### Research Paper 2020-12-31

#### Effect of Pulsed Magnetic Field Stimulation of Bio-Conductance Response on The Human Meridian Circulatory System

Hyunsook LEE*

Abstract : This study aims to investigate the effect of pulsed magnetic field (PMF) stimulus on the circulation in the pericardium meridian system (AMS) by means of EAV (electroacupuncture according to Voll) and the galvanic skin response (GSR). The PMF stimulus was applied to PC8 at least three times a week for one month in order to see the continuous effect of PMF stimulation. The Max value measured at every biological active point except PC9 was found to be close to the normal range of 45 ~ 58 one month later. Therefore, PMF stimulation seems to be very effective in improving the function of the tenon-tissue connected to the pericadium meridian in Oriental medicine. The magnetic flux change due to the PMF is thought to lead to a strong stimulus at the acupoints, which have a lower impedance than the surrounding tissues and affects the current in the cell tissue. For further use of our results in meridian diagnosis, additional experiments on the subject for diverse diseases are required, as is a study of the changes in PMF intensity, transition time and stimulation duration.

• ### Research Paper 2020-12-31

#### Electromagnetic Lensing by Born-Infeld type Electric Charge

Jin Young KIM*

Abstract : Light traveling in an electromagnetic field is not affected by the presence of the electromagnetic field in Maxwell electrodynamics, which is linear. However, in quantum electrodynamics, nonlinear terms are created in the effective action by quantum fluctuation and the propagation of light is affected by the external electromagnetic field. In Born-Infeld electrodynamics introduced to solve the divergence of the electromagnetic field at the origin, the permittivity and the permeability of vacuum in the presence of an external electromagnetic field are not one by non-linearity. We study the bending of a light ray passing a strong external electric field in generalized Born-Infeld electrodynamics, which includes the quantum effect. When a light ray moves around electrically charged objects like a charged black hole or an atomic nucleus, the path of light can be bent by the gradient of the effective index of refraction. We use the trajectory equation based on geometric optics for weak lensing, in which the impact parameter is large compared to the characteristic length of the Born-Infeld parameter, to compute the bending angle.

## Current Issue

• ### A Study on the Measurement and Analysis of the Impedance of Various Materials

Jong-Ho PARK*

New Phys.: Sae Mulli 2019; 69(1): 1-15
https://doi.org/10.3938/NPSM.69.1

• ### Study of the Shapes of CdSe/CdS Nanocrystals by Using Raman Spectroscopy and the Stokes Shift

Seong-Wook PARK, Hoon-Hyun CHO, Dong-Sun YOO, Il-Gon KIM*

New Phys.: Sae Mulli 2019; 69(1): 16-24
https://doi.org/10.3938/NPSM.69.16

• ### Dependences of the Near-Field Characteristics of the Nano-Gap Structure on the Difference between Pentagonal and Circular Nano-Wires: A Numerical Study

Vasanthan DEVARAJ, Jong-Min LEE, Chun Tae KIM, Won-Geun KIM, Jin-Woo OH*

New Phys.: Sae Mulli 2019; 69(1): 25-30
https://doi.org/10.3938/NPSM.69.25