• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1204-1208
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• 2012

A new photoelectrode composed of $Sb_6O_{13}$ nanoparticles with the size of 20-30 nm has been prepared via thermolysis of a colloidal antimony pentoxide tetrahydrate ($Sb_2O_5{\cdot}4H_2O$) suspension. The $Sb_6O_{13}$ electrode showed good semiconducting properties applicable to dye-sensitized solar cells (DSSCs); the energy band gap was estimated to be $3.05{\pm}0.5$ eV and the position of conduction band edge was close to those of $TiO_2$ and ZnO. The DSSC assembled with the $Sb_6O_{13}$ photoelectrode and a conventional ruthenium-dye (N719) exhibited the overall photo-current conversion efficiency of 0.74% ($V_{oc}$ = 0.76 V, $J_{sc}=1.99\;mAcm{-2}$, fill factor = 0.49) under AM 1.5, $100\;mWcm^{-2}$ illumination.

• 한국결정성장학회지
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• 제13권3호
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• pp.122-126
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• 2003

본 연구에서는 두께가 0.7 $\mu \textrm{m}$인 $Zn_{0.86}Mn_{0.14}$Te 에피막을 GaAs(100) 기판 위에 열벽 적층 성장하였다. 선택에칭용액에 의하여 GaAs 기판이 제거된 X-선 회절 패턴으로부터 $Zn_{0.86}Mn_{0.14}$Te에피막의 결정구조는 zincblende 이었으며 격자상수는 6.140 $\AA$으로 계산되었다. 이러한 격자상수 값과 Vegard 법칙으로부터 Mn의 조성비 x=0.14임을 알았다. 성장된 에피막의 결정성은 이중결정요동 곡선의 반폭치 값이 256 arcsec인 것으로부터 양호하다는 것이 확인되었다 상온에서 10K 까지 $Zn_{0.86}Mn_{0.14}$Te에피막의 온도에 따른 띠 간격 에너지를 측정하기 위하여 투과 스펙트럼으로부터 흡수 스펙트럼이 얻어졌다 온도가 감소할수록 흡수 스펙트럼에서 강하게 흡수가 일어나는 영역은 에너지가 큰 쪽을 향하여 이동하였고 흡쑤단 근처에서 자유 엑시톤 형성을 의미하는 흡수 피크가 생겨났다. $Zn_{0.86}Mn_{0.14}$Te에피막의 온도에 따른 자유 엑시톤 피크 에너지로부터 OK와 300 K일 때 띠 간격 에너지는 각각 2.4947 eV와 2.330 eV로 구하여졌다. 10 K에서 기판이 제거된 $Zn_{0.86}Mn_{0.14}$Te 에피막의 흡수 스펙트럼의 자유 엑시톤 피크 에너지는 광발광 피크 에너지보다 15.4 meV 정도 크다. 이 에너지 차이는 흡수 스펙트럼과 발광 피크 사이의 에너지 차이를 의미하는 Stokes shift를 나타낸다.

• 센서학회지
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• 제23권2호
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• pp.134-141
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• 2014

A stoichiometric mixture of evaporating materials for $BaIn_2Se_4$ epilayers was prepared from horizontal electric furnace. To obtain the single crystal thin films, $BaIn_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the epilayers was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $BaIn_2Se_4$ epilayers measured from Hall effect by van der Pauw method are $8.94{\times}10^{17}cm^{-3}$ and 343 $cm^2/vs$ at 293 K, respectively. The temperature dependence of the energy band gap of the $BaIn_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.6261 eV-$(4.9825{\times}10^{-3}eV/K)T^2/(T+558 K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $BaIn_2Se_4$ have been estimated to be 116 meV and 175.9 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $BaIn_2Se_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-$, $B_1$-exciton for n = 1 and $C_{21}$-exciton peaks for n=21.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.50-53
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• 1995

In this paper we have obtained property by considering the change of optical energy gap as a function of photo-does for exposing photo on Ag/a-Se$\sub$75/Ge$\sub$25/ thin films. This U-type property was obsered for all photo-exposing except for blu-pass filtered Hg lamep. Expecially, very large band shift(~0.3[eV]) is obtained by exposing He-Ne laser (6328[${\AA}$]). It is impossible to explain this property for exposing He-Ne and semiconductor laser through DWP model, which was explained for photo-exposing above the energy gap. Therefore we suggest a new modified model of DWP model for Ag/a-Se$\sub$75/Ge$\sub$25/ bilayer thin films.

• Journal of Electrical Engineering and Technology
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• 제5권4호
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• pp.637-639
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• 2010

Hexagonal boron nitride (BN) films were prepared. The process involved, spraying BN powder-dispersed $H_3BO_4-BCl_3$-ethyl alcohol solution on quartz plates, and the drying off quartz plates before, and annealing at $1070^{\circ}C$ in a nitrogen atmosphere. The optical energy band gap of the BN films was 5.28 eV. Photoluminescence peaks with energies of 3.44, 3.16, 2.97, and 2.35 eV at 10 K were observed and analyzed. Accordingly, these have resulted from donor-acceptor pair recombinations.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.128-132
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• 2013

L-Arginine semi-oxalate (LASO) single crystal has been grown by solution growth technique at room temperature. The crystal structure and lattice parameters were determined for the grown crystal by single crystal X-ray diffraction studies. Photoluminescence studies confirm the violet fluorescence emission peak at 395 nm. Optical constants like band gap, refractive index, reflectance, extinction coefficient and electric susceptibility were determined from UV-VIS-NIR spectrum. The dielectric constant, dielectric loss and ac conductivity of the compound were calculated at different temperatures and frequencies to analyze the electrical properties. The solid state parameters such as plasma energy, Penn gap, Fermi energy and polarizability were calculated to analyze second harmonic generation (SHG). Nonlinear optical property was discussed to confirm the SHG efficiency of the grown crystal.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.607-608
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• 2005

In this paper, author describe the undoped and $Co^{2+}$(0.5mole%) doped $Cd_4SnSe_6$ single crystals were grown by the chemical transport reaction(CTR) method. The grown single crystals crystallize in the monoclinic structure of space group Cc and have the direct band gap structure. The energy gaps of them are 1.68 eV for $Cd_4SnSe_6$ and 1.50 eV for $Cd_4SnSe_6:Co^{2+}$ at 300K respectively.

• 대한화학회지
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• 제63권5호
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• pp.352-359
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• 2019

The most important parameter of organic molecules for energy harvesting application focuses mainly on their band gap (HOMO-LUMO). In this report, we synthesized differently substituted 1,3,5-triazine based organic molecule which on future processing can be used in organic electronics like solar cells and OLED's. The energy gap of the synthesized novel analogue was calculated using cyclic voltammetry, UV-Visible spectroscopy and compared with density functional theory (DFT) studies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.459.1-459.1
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• 2014

Because both $TiO_2$ and ZnO has superior characteristic optically and electrically, there are various of research for these materials. However, they have large band gap energy which correspond with not visible light, but UV light. To make up for this disadvantage, Quantum dots (CdS, CdSe) which can absorb the visible light could be deposited on $ZnO/TiO_2$ nanostructure so that the the photoelectrochecmical cell can absorb the light that has larger region of wavelength. Both $TiO_2$ and ZnO can be grown to one-dimensional nanowire structure at low temperature through solutional method. Three-dimensional hierarcical $ZnO/TiO_2$ nanostructure is fabricated by applying these process. Large surface area of this structure make the light absorbed more efficiently. Through type 2 like-cascade energy band structure of nanostructure, the efficient separation of electron-hole pairs is expected. Photoelectrochemical charateristics are found by using these nanostructure to photoelectrode.

• 한국표면공학회지
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• 제29권6호
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• pp.660-665
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• 1996

Thin films of indium oxide and indium tin oxide have been prepared by d.c. magnetron sputtering onto the fused silica substrates kept at 90, 200 and $300^{\circ}C$. In order to elucidate the optical absorption process in low energy region below 3 eV, we have analyzed the absorption coefficients obtained from reflectance and transmittance measurements for these films based on the Lucovsky model. It has been found for the first time that a defect center in the band gap is located at 0.8~1.4 eV below the Fermi level in all films and arises from oxygen vacancies in their films. The optical absorption in low energy region is explained to be dominated by the transition of electrons trapped at the positively charged (+2e) oxygen vacancies with s-like nature to the conduction band formed from the 5s-orbit in indium atoms.