Mn 조성 변화에 따른 육방정 Cd1-xMnxS/GaAs(111) 박막의 분광학적 특성 연구

김대중,이종원 한국물리학회 2023 새물리 Vol.73 No.8

In this study, hexagonal Cd1-xMnxS (h-CdMnS) thin films with different Mn compositions were grown on GaAs(111) substrates using hot-wall epitaxy. The energy gap of the grown films was obtained through the reflection spectrum, and the crystal structure and quality were examined through X-ray diffraction (XRD) and high-resolution XRD. To obtain insights into the spectroscopic characteristics of the grown films, spectroscopic ellipsometry (SE) was employed, and the critical structures were identified. The pseudodielectric constants ε1(E) and ε2(E) were derived from the obtained critical structures. Additionally, using the second derivatives of the pseudodielectric constants, the variation of critical structures was analyzed as a function of Mn composition. In particular, the energy bandgap (Eg) obtained from the reflection spectrum and the energy bandgap (E0) obtained from SE measurements were compared and analyzed for the h-CdMnS/GaAs(111). 본 연구에서는 열벽적층성장법(hot-wall epitaxy:HWE)을 이용하여 Mn 조성 변화에 따른 육방정 Cd1-xMnxS 박막을 GaAs(111) 기판 위에 성장시켰다. 성장된 박막은 반사 측정을 수행하여 에너지갭을 구하였고, XRD와 고분해능 XRD (HRXRD) 측정을 이용하여 박막의 결정구조와 결정성을 알아보았다. 박막의 분광학적 특성을 더 심층적으로 평가하기 위하여 타원편광분석법(spectroscopic ellipsometry:SE)을 이용하여 임계점 구조를 관측하였다. 측정된 SE 데이터를 분석하여 박막의 복소 유사유전상수 ε1(E), ε2(E)를 구했으며, 이들 분광학적 데이터의 이계도함수를 이용하여 Mn 조성 변화에 따른 임계점 구조의 변화를 관측하고 분석하였다. 특히, 본 연구에서는 육방정 Cd1-xMnxS/GaAs(111) 박막의 반사측정으로부터 얻은 에너지갭(Eg)과 SE를 이용하여 얻은 에너지갭(E0)을 비교하고 분석하였다.

Optical investigation of oxygen defect states in SrTiO3 epitaxial thin films

서윤경,이윤상,이상아,최우석 한국물리학회 2017 Current Applied Physics Vol.17 No.8

We investigated oxygen defect states in SrTiO3 (STO) thin films by using photoluminescence spectroscopy and spectroscopic ellipsometry. The oxygen-deficient STO homoepitaxial films were fabricated by using different oxygen partial pressures and flow rates for controlling the amount of oxygen vacancies systematically. The visible emission and absorption increased simultaneously with increasing oxygen vacancy concentration in the STO thin films. Given the absolute values of the optical constants, we discussed the origins of the visible absorption features in the STO thin films, in relation to the defect formation and related electronic reconstruction.

Optical investigation of oxygen defect states in SrTiO₃ epitaxial thin films

Seo, I.W.,Lee, Y.S.,Lee, S.A.,Choi, W.S. Elsevier 2017 Current Applied Physics Vol.17 No.8

<P>We investigated oxygen defect states in SrTiO3 (STO) thin films by using photoluminescence spectroscopy and spectroscopic ellipsometry. The oxygen-deficient STO homoepitaxial films were fabricated by using different oxygen partial pressures and flow rates for controlling the amount of oxygen vacancies systematically. The visible emission and absorption increased simultaneously with increasing oxygen vacancy concentration in the STO thin films. Given the absolute values of the optical constants, we discussed the origins of the visible absorption features in the STO thin films, in relation to the defect formation and related electronic reconstruction. (C) 2017 Elsevier B.V. All rights reserved.</P>

Optical Constants and Dispersion Parameters of CdS Thin Film Prepared by Chemical Bath Deposition

박욱동 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.4

CdS thin film was prepared on glass substrate by chemical bath deposition in an alkaline solution. The optical properties of CdS thin film were investigated using spectroscopic ellipsometry. The real (ε1) and imaginary (ε2) parts of the complex dielectric function ε(E)=ε1(E) + iε2(E), the refractive index n(E), and the extinction coefficient k(E) of CdS thin film were obtained from spectroscopic ellipsometry. The normal-incidence reflectivity R(E) and absorption coefficient α(E) of CdS thin film were obtained using the refractive index and extinction coefficient. The critical points E0 and E1 of CdS thin film were shown in spectra of the dielectric function and optical constants of refractive index,extinction coefficient, normal-incidence reflectivity, and absorption coefficient. The dispersion of refractive index was analyzed by the Wemple-DiDomenico single-oscillator model.

Optical and Structural Analysis of Zinc Oxysulfide Digital Alloys Grown by Atomic Layer Deposition

Sou Young Yu,Mostafa A Hassan,Muhammad Ali Johar,Sang-Wan Ryu 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5

We investigated the optical and structural properties of ZnOS digital alloy grown on Si by atomic layer deposition. The refractive index and extinction coecient were evaluated using spectroscopic ellipsometry. ZnOS alloy film shows a strong absorption tail extended to the below band gap regime, which is attributed to a high density of band tail states formed within the band gap owing to the amorphous crystallinity. The ZnOS alloy exhibits a large Urbach energy of 210 - 540 meV. After high-temperature annealing, the band tail states are reduced with a decrease in lattice disorder, which is confirmed by enhanced X-ray diffraction peaks.

Approximated dielectric tensor of the biaxial α-SnSe crystal

Le Long Van,Nguyen Hoang Tung,Kim Tae Jung,Nguyen Xuan Au,Kim Young Dong 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.4

We present the principal components of the dielectric tensor for α-SnSe biaxial single crystal in the spectral range from 0.74 to 6.42 eV at room temperature (300 K) using spectroscopic ellipsometry. Aspnes’ first-order approximation method was applied to obtain approximated pseudodielectric response from the pseudodielectric tensor measured at an angle of incidence of ϕ = 68.8°. Multilayer calculations were then performed to extract the pure dielectric tensor without surface roughness artifacts. The Tauc–Lorentz model was applied to describe the critical point structures, and the optical constants along the principal axes of biaxial α-SnSe single crystal can be now calculated at arbitrary wavelength for device applications.

Optical Constants and Dispersion Parameters of CdS Thin Film Prepared by Chemical Bath Deposition

Park, Wug-Dong The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.4

CdS thin film was prepared on glass substrate by chemical bath deposition in an alkaline solution. The optical properties of CdS thin film were investigated using spectroscopic ellipsometry. The real (${\varepsilon}_1$) and imaginary (${\varepsilon}_2$) parts of the complex dielectric function ${\varepsilon}(E)={\varepsilon}_1(E)+i{\varepsilon}_2(E)$, the refractive index n(E), and the extinction coefficient k(E) of CdS thin film were obtained from spectroscopic ellipsometry. The normal-incidence reflectivity R(E) and absorption coefficient ${\alpha}(E)$ of CdS thin film were obtained using the refractive index and extinction coefficient. The critical points $E_0$ and $E_1$ of CdS thin film were shown in spectra of the dielectric function and optical constants of refractive index, extinction coefficient, normal-incidence reflectivity, and absorption coefficient. The dispersion of refractive index was analyzed by the Wemple-DiDomenico single-oscillator model.

Dielectric Function and Critical Points of SnS0.52Se0.48 in the Temperature Range from 27 to 350 K

Kim Tae Jung,Nguyen Xuan Au,Kim Bogyu,Kim Kyujin,Lee Wonjun,Kim Young Dong,르반롱,Nguyen Hoang Tung 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.11

We report the dielectric function ε = ε1+iε2 and the critical point (CP) energies of the orthorhombic SnS0.52Se0.48 alloy for the zigzag (a) and the armchair (b) directions in the spectral energy range from 0.74 to 6.42 eV and the temperature range from 27 to 350 K using spectroscopic ellipsometry. The CP energies were determined from the 2nd derivative spectra by using the standard analytic method. We observed sharpenings and blue-shifts of the CPs with decreasing temperature. We found thirteen and twelve CPs for the a- and the b-directions, respectively, at the lowest temperature while only eight and nine CPs were detected at room temperature. Also, an exciton effect was observed only in the armchair direction at low temperatures. The temperature dependences of the CP energies were determined by fitting the data to a phenomenological expression that contain the Bose-Einstein statistical factor and the temperature coefficient to describe the electron-phonon interaction.

Modeling of the Optical Properties of Monolayer WS2

Kim Tae Jung,Le Van Long,Nguyen Hoang Tung,Nguyen Xuan Au,Kim Young Dong 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.4

We report parametric modeling of the optical properties of monolayer WS2 so its dielectric response can be calculated at temperatures from 41 to 300 K from 1.5 to 6 eV. Parameterization of dielectric function was performed by dielectric-function parametric model, using previously reported dielectric function data which was obtained by spectroscopic ellipsometry. We interpolated the obtained parameters by using cubic polynomials to reconstruct optical properties at arbitrary temperatures. Blue shifts of the bandgap energies and reductions of linewidths of the critical point structures are clearly observed. Given these results, refractive indices and absorption coefficients of the monolayer WS2 follow also at arbitrary temperatures.

분광타원법을 이용한 PDP용 ITO 박막의 패턴 분석

윤희삼,김상열 한국광학회 2003 한국광학회지 Vol.14 No.3

분광타원법을 이용하여 PDP용 ITO박막의 광학상수 및 패턴을 분석하였다. ITO 박막의 광물성은 로렌쯔 진동자 모델을 사용하고 ITO의 패턴에 의한 효과는 전체빔이 ITO와 유리기층을 덮는 면적비 가중치를 가진 반사율 평균방법으로 반영시켰다. PDP 다층박막을 구성하고 있는 유리기층 위의 ITO박막 패턴이 타원데이터에 미치는 영향을 분석하여 ITO가 패턴에서 차지하는 면적비를 결정하였다. 측정된 분광타원데이터에 최적맞춤한 ITO의 상대면적값이 예측값과 보이는 차이를 검토함으로써 분광타원법을 사용한 ITO패턴분석의 한계와 이를 극복하는 방법을 제시하였다. We studied patterned ITO layers of PDP thin films on glass substrates using spectroscopic ellipsometry. The optical property of ITO is expressed with the optical model based on two Lorentz oscillators. The effect of patterned ITO is calculated by taking the weighted average of reflectance in proportion to ITO coverage. The relative coverage of ITO is determined by using the model analysis of spectroellipsometric data. The difference of ITO coverage obtained by the best-fit model analysis of ellipsometric spectra to the expected one is critically examined and suggestions are made to minimize the observed discrepancy.