• Title/Summary/Keyword: Donor-doped

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Comparison of Optical Properties of Ga-doped and Ag-doped ZnO Nanowire Measured at Low Temperature

  • Lee, Sang Yeol
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.5
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    • pp.262-264
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    • 2014
  • Pristine ZnO, 3 wt.% Ga-doped (3GZO) and 3 wt.% Ag-doped (3SZO) ZnO nanowires (NWs) were grown using the hot-walled pulse laser deposition (HW-PLD) technique. The doping of Ga and Ag in ZnO NWs was observed by analyzing the optical and chemical properties. We optimized the synthesis conditions, including processing temperature, time, gas flow, and distance between target and substrate for the growth of pristine and doped ZnO NWs. The diameter and length of pristine and doped ZnO NWs were controlled under 200 nm and several ${\mu}m$, respectively. Low temperature photoluminescence (PL) was performed to observe the optical property of doped NWs. We clearly observed the shift of the near band edge (NBE) emission by using low temperature PL. In the case of 3GZO and 3SZO NWs, the center photon energy of the NBE emissions shifted to low energy direction using the Burstein Moss effect. A strong donor-bound exciton peak was found in 3 GZO NWs, while an acceptor-bound exciton peak was found in 3SZO NWs. X-ray photoelectron spectroscopy (XPS) also indicated that the shift of binding energy was mainly attributed to the interaction between the metal ion and ZnO NWs.

Microwave Dielectric Properties of Donor doped Zr0.8Sn0.2TiO4 Ceramics (Donor Dopant 첨가 Zr0.8Sn0.2TiO4 세라믹스의 마이크로파 유전특성)

  • 김윤호
    • Journal of the Microelectronics and Packaging Society
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    • v.2 no.2
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    • pp.31-40
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    • 1995
  • Donor dopant로 WO3, Ta2O5 및 Nb2O5를 첨가한 Zr0.8Sn0.2TiO4 세라믹스의 유전상수 $\varepsilon$r 품 질계수 Q 및 공진주파수의 온도계수 rf에 대하여 연구하였다. 139$0^{\circ}C$에서 32시간 소결시 donor dopant 첨가량에 따른 ZST의 유전상수는 소결밀도의 변화 거동과 잘 일치하였다. 5.5 GHz에서 측정 한 ZST의 품질계수 Q는 ~0.5 mol% WO3 Ta2O5 및 Nb2O5 첨가에 의해 6800에서 8500 정도로 증가 하였다. ZST의 $\tau$f는 0.3 mol%까지의 WO3 첨가량 증가에 따라 0 ppm/$^{\circ}C$에서 -4.6 ppm/$^{\circ}C$까지 음 의 값으로 직선적으로 감소하였으며 0.4 mol% 범위의 Ta2O5 및 Nb2O5 첨가에 의해 -7 ppm/$^{\circ}C$ 까지 직선적으로 감소하였다.

Microstructural Characterization and Dielectric Properties of Barium Titanate Solid Solutions with Donor Dopants

  • Kim, Yeon-Jung;Hyun, June-Won;Kim, Hee-Soo;Lee, Joo-Ho;Yun, Mi-Young;Noh, S.J.;Ahn, Yong-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.30 no.6
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    • pp.1267-1273
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    • 2009
  • The correlation between the sintering temperature and dielectric properties in the $Nb^{5+}\;and\;Ta^{5+}$ doped BaTi$O_3$ solid solutions have been investigated. The samples were sintered at temperatures ranging from 1250 to 1350 ${^{\circ}C}$ for 4 h in air. SEM, XRD and SEM/EDS techniques were used to examine the structure of the samples with particular focus on the incorporation of $Nb^{5+}\;and\;Ta^{5+}$ ions into the BaTi$O_3$ crystal lattice. The X-ray diffraction peaks of (111), (200) and (002) planes of BaTi$O_3$ solid solution doped with different fractions of $Nb^{5+}\;and\;Ta^{5+}$ were investigated. The dielectric properties were analyzed and the relationship between the properties and structure of doped BaTi$O_3$ was established. The fine-grain and high density of the doped BaTi$O_3$ ceramics resulted in excellent dielectric properties. The dielectric properties of this solid solutions were improved by adding a small amount of dopants. The transition temperature of the 1.0 mole% $Ta^{5+}$ doped BaTi$O_3$ solid solution was $\sim$110 ${^{\circ}C}$ with a dielectric constant of 3000 at room temperature. At temperatures above the Curie temperatures, the dielectric constant followed the Curie-Weiss law.

The 1320-nm Excited FT-Raman Spectra of Lightly Iodine-Doped trans-Polyacetylene

  • Kim, Jin-Yeol;Yukio Furukawa;Akira Sakamoto;Mitsuo Tasumi
    • Macromolecular Research
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    • v.10 no.5
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    • pp.286-290
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    • 2002
  • The FT-Raman spectra of trans-polyacetylene films doped lightly with iodine were obtained with the 1320-nm laser line. The observed Raman bands are attributed to positively charged domains created by acceptor doping. The observed Raman wavenumbers of the V$_2$, (CC stretch), V$_3$, and V$_4$ bands (mixed of CC stretch and CH in-plan bending) of iodine-doped form are slightly higher than those of the corresponding bands of pristine trans-polyacetylene, whereas the contrary is the case for V$_1$, and (C=C stretch) of iodine-doped form. In particular, these upshifts of the V$_2$ and V$_3$ bands are distinguished from the downshifts of these bands in donor doping. The origin of doping induced Raman bands is discussed in terms of solitons and polarons.

Enhanced Light Harvesting from F$\ddot{o}$rst-type resonance Energy Transfer in the Quasi-Solid State Dye-Sensitized Solar Cells (F$\ddot{o}$rst energy transfer 를 적용한 준고체 DSSC 의 효율향상)

  • Cheon, Jong Hun;Lee, Jeong Gwan;Yang, Hyeon Seok;Kim, Jae Hong
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.117.1-117.1
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    • 2011
  • We have demonstrated Forst-type resonance energy transfer (FRET) in the quasi-solid type dye-sensitized solar cells between organic fluorescence materials as an energy donor doped in polymeric gel electrolyte and ruthenium complex as an energy acceptor on surface of $TiO_2$. The strong spectral overlap of emission/absorption of energy donor and acceptor is required to get high FRET efficiency. The judicious choice of energy donor allows the enhancement of light harvesting characters of energy acceptor in quasi-solid dye sensitized solar cells which increase the power conversion efficiency. The enhanced light harvesting effect by the judicious choice/design of the fluorescence materials and sensitizing dyes permits the enhancement of photovoltaic performance of DSSC.

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A New Diarylethene with Donor-acceptor Group for Reversible Photo-induced Electrochemical Switching

  • Kim, Eun-Kyoung;Kim, Mi-Young;Kim, Kyong-Tae
    • Bulletin of the Korean Chemical Society
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    • v.29 no.4
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    • pp.827-832
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    • 2008
  • A new diarylethene compound with donor and acceptor substituent was synthesized from 2,3-bis(2-methylbenzo[b]thiophene-3-yl)hexafluorocyclopentene (BTF) over 5 steps. The donor-acceptor structured BTF compound (TBTFE) showed spectral change to a longer wavelength through photochromism with a high cyclization quantum yield (0.56). The 3,4-ethylenedioxythiophene (T) and carboethoxy (E) groups directly connected to BTF unit promoted electrical change accompanied with the photoisomerization of the BTF unit. Photo-induced electrical switching was achieved from a photocell containing TBTFE doped polymer film, which showed reversible and stable current change over repeated cycles by the alternative UV/Vis irradiation, as estimated by the I-V plot.

Characteristic of P doped ZnO-based thin film transistor by DC magnetron sputtering

  • Lee, Sih;Moon, Yeon-Keon;Moon, Dae-Yong;Kim, Woong-Sun;Kim, Kyung-Taek;Park, Jong-Wan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.540-542
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    • 2009
  • Phosphorus doped ZnO (PZO) thin films were deposited on $SiO_2$/n-Si substrates using DC magnetron sputtering system varying oxygen partial pressures from 0 to 40 % under Ar atmosphere. The deposited films showed reduced n-type conductivity due to the compensating donor effects by phosphorus dopant. The bias-time stability shows relatively good stability over bias and time comparing to un-doped ZnO-based TFTs.

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Temperature-dependent photoluminescence study on aluminum-doped nanocrystalline ZnO thin films by sol-gel dip-coating method

  • Nam, Giwoong;Park, Hyunggil;Yoon, Hyunsik;Kim, Soaram;Leem, Jae-Young
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2012.11a
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    • pp.131-133
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    • 2012
  • The photoluminescence (PT) properties of Al-doped ZnO thin films grown by the sol-gel dip-coating method have been investigated. At 12 K, nine distinct PL peaks were observed at 2.037, 2.592, 2.832, 3.027, 3.177, 3.216, 3.260, 3.303, and 3.354 eV. The deep-level emissions (2.037, 2.592, 2.832, and 3.027 eV) were attributed to native defects. The near-band-edge (NBE) emission peaks at 3.354, 3.303, 3.260, 3.216, and 3.177 eV were attributed to the emission of the neutral-donor-bound excitons (D0X), two-electron satellite (TES), free-to-neutral-acceptors (e,A0), donor-acceptor pairs (DAP), and second-order longitudinal optical (2LO) phonon replicas of the TES (TES-2LO), respectively. According to Haynes' empirical rule, we calculated the energy of a free exciton (FX) to be 3.374 eV. The thermal activation energy for D0X in the nanocrystalline ZnO thin film was found to be ~25 meV, corresponding to the thermal dissociation energy required for D0X transitions.

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