• Proceedings of the Korean Vacuum Society Conference
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• 2004.08a
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• pp.237-237
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• 2004

• Transactions on Electrical and Electronic Materials
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• v.5 no.5
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• pp.173-179
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• 2004

The influence of heavily Si impurity doping in the GaN barrier of InGaN/GaN multi-quantum well structures of blue light emitting diodes were investigated by growing samples in metal-organic chemical vapor deposition. The delta-doped sample was compared to the sample with the undoped barrier. The delta-doped sample shows the tunneling behavior and forms the energy level of 0.32 eV for tunneling and the photoemission of the 450-nm band. The photo-luminescence shows the blue-shifted broad band of the radiative transition due to the inclusion of Si delta-doped layer indicating that the delta doping effect acts to form the higher energy level than that of quantum well. The dislocation may provide the carrier tunneling channel and plays as a source of acceptor. During the tunneling of hot carrier, there was no light emission.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.417-420
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• 2004

The electrical effects of dry-etch on n-type GaN by an inductively coupled $Cl_2/CH_4/H_2/Ar$ plasma were investigated as a function of ion energy, by means of ohmic and Schottky metallization method. The specific contact resistivity(${\rho}_c$) of ohmic contact was decreased, while the leakage current in Schottky diode was increased with increasing ion energy due to the preferential sputtering of nitrogen. At a higher rf power, an additional effect of damage was found on the etched sample, which was sensitive to the dopant concentration in terms of the ${\rho}_c$ of ohmic contact. This was attributed to the effects such as the formation of deep acceptor as well as the electron-enriched surface layer within the depletion layer. Furthermore, thermal annealing process enhanced the ohmic and Schottky property of heavily damaged surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.10
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• pp.642-647
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• 2014

For feasible study of opto-electrical application regarding to oxide semiconductor, we implemented the N doped ZnO growth using a atomic layer deposition technique. The p-type ZnO deposition, necessary for ZnO-based optoelectronics, has considered to be very difficulty due to sufficiently deep acceptor location and self-compensating process on doping. Various sources of N such as $N_2$, $NH_3$, NO, and $NO_2$ and deposition techniques have been used to fabricate p-type ZnO. Hall measurement showed that p-type ZnO was prepared in condition with low deposition temperature and dopant concentration. From the evaluation of photoluminescence spectroscopy, we could observe defect formation formed by N dopant. In this paper, we exhibited the electrical and optical properties of N-doped ZnO thin films grown by atomic layer deposition with $NH_3OH$ doping source.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.509-514
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• 2020

The two key variables of an Si solar cell, i.e., emitter (n-type window layer) and base (p-type substrate) doping levels or concentrations, are studied using Medici, a 2-dimensional semiconductor device simulation tool. The substrate is p-type and 150 ㎛ thick, the pn junction is 2 ㎛ from the front surface, and the cell is lit on the front surface. The doping concentration ranges from 1 × 10¹⁰ cm^-3 to 1 × 10²⁰ cm^-3 for both emitter and base, resulting in a matrix of 11 by 11 or a total of 121 data points. With respect to increasing donor concentration (Nd) in the emitter, the open-circuit voltage (Voc) is little affected throughout, and the short-circuit current (Isc) is affected only at a very high levels of Nd, exceeding 1 × 10¹⁹ cm^-3, dropping abruptly by about 12%, i.e., from Isc = 6.05 × 10^-9 A·㎛^-1, at Nd = 1 × 10¹⁹ cm^-3 to Isc = 5.35 × 10^-9 A·㎛^-1 at Nd = 1 × 10²⁰ cm^-3, likely due to minority-carrier, or hole, recombination at the very high doping level. With respect to increasing acceptor concentration (Na) in the base, Isc is little affected throughout, but Voc increases steadily, i.e, from Voc = 0.29 V at Na = 1 × 10¹² cm^-3 to 0.69 V at Na = 1 × 10¹⁸ cm^-3. On average, with an order increase in Na, Voc increases by about 0.07 V, likely due to narrowing of the depletion layer and lowering of the carrier recombination at the pn junction. At the maximum output power (Pmax), a peak value of 3.25 × 10^-2 W·cm^-2 or 32.5 mW·cm^-2 is observed at the doping combination of Nd = 1 × 10¹⁹ cm^-3, a level at which Si is degenerate (being metal-like), and Na = 1 × 10¹⁷ cm^-3, and minimum values of near zero are observed at very low levels of Nd ≤ 1 × 10¹³ cm^-3. This wide variation in Pmax, even within a given kind of solar cell, indicates that selecting an optimal combination of donor and acceptor doping concentrations is likely most important in solar cell engineering.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.150-154
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• 2019

This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$, which has a rhombohedral-tetragonal phase boundary composition. $MnO_2$ and CuO-added $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$ ceramics sintered at a relatively low temperature of $1020^{\circ}C$ show a pure perovskite phase with no secondary phase. As the addition of $MnO_2$ and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of $MnO_2$.

• Korean Journal of Materials Research
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• v.34 no.7
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• pp.321-329
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• 2024

In this work, a series of BaTiO₃-based ceramic materials, Ba(Al_0.5Nb_0.5)_xTi_1-xO₃ (x = 0, 0.04, 0.06, 0.08), were synthesized using a standard solid-state reaction technique. X-ray diffraction profiles indicated that the Al+Nb co-doping into BaTiO₃ does not change the crystal structure significantly with a doping concentration up to 8 %. The doping ions exist in Al³⁺ and Nb⁵⁺ chemical states, as revealed by X-ray photoelectron spectroscopy. The frequency-dependent complex dielectric properties and electric modulus were studied in the temperature range of 100~380 K. A colossal dielectric permittivity (>1.5 × 10⁴) and low dielectric loss (<0.01) were demonstrated at the optimal dopant concentration x = 0.04. The observed dielectric behavior of Ba(Al_0.5Nb_0.5)_xTi_1-xO₃ ceramics can be attributed to the Universal Dielectric Response. The complex electric modulus spectra indicated the grains exhibited a significant decrease in capacitance and permittivity with increasing co-doping concentration. Our results provide insight into the roles of donor and acceptor co-doping on the properties of BaTiO₃-based ceramics, which is important for dielectric and energy storage applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.15-16
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• 2008

We have grown N-doped ZnO thin films on sapphire substrate by employing dielectric barrier discharge in pulsed laser deposition (DBD-PLD). DBD guarantees an effective way for massive in-situ generation of N-plasma under the conventional PLD process condition. Low-temperature photoluminescence spectra of the N-doped ZnO film provided near band-edge emission after thermal annealing process. The emission peak was resolved by Gaussian fitting and showed a dominant acceptor-bound exciton peak ($A^0X$) that indicated the successful p-type doping of ZnO with N.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.373-377
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• 2015

이 연구에서는 원자 궤도 함수 기반 DFT 전자구조 계산을 이용해서 최근 각광받고 있는 이차원 물질인 MoS2 monolayer의 S 자리와 Mo 자리에 각각 전자가가 다른 원자를 치환하였을 때의 도핑 특성을 Density of States (DOSs)와 밴드구조 등의 전자구조를 통해 분석해 보았다. S자리에 Cl, Si, I, B, C, Mo 자리에는 Hf, Ta, 그리고 Re을 치환해 보았으며 계산 결과 S자리에 Cl을 치환했을 때 가장 얕은 acceptor level (VBM으로부터 0.08 eV)이 형성되었으며, Mo자리에 Re를 치환했을 때에는 resonant state를 형성하였다. 또한 Mo자리에 Ta를 치환했을 ? 가장 얕은 donor level (CBM으로부터 0.02 eV)가 형성되었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.334-340
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• 1997

Electric and dielectric properties of the $SrTiO_3$films have been studied. The influence of impurities on $SrTiO_3$ films was evaluated to reduce the leakage current density. Acceptor doping, with a small concentration of Fe or Cr, has led to a substantial improvement to $10^{-9}$ order in the leakage current density. The experimental results can be explained by a model in which oxygen vacancies are the key defects responsible for the leakage current. The $SrTiO_3$ film 200 nm in thickness with 5 mol% excess SrO fabricated in $Ar/O_2$ at $550^{\circ}C$ obtained the lowest leakage current density $1.0 {\times} 1.0 A/\textrm{cm}^2$. The improved results can be introduced into the capacitor dielectric of giga bit DRAM memories.