• 한국전자파학회논문지
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• 제14권12호
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• pp.1335-1340
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• 2003

본 논문에서는 쇼트키 장벽 빔 리드 다이오드와 180$^{\circ}$hybrid coupler를 이용하여 24 GHz 대역에서 동작하는 단일 평형 다이오드 주파수 혼합기를 설계 및 제작하였다. 근거리 차량의 거리와 속도 탐지용 호모다인 FMCW 레이더의 용도에 적합하도록 대역폭은 100MHz이내에서 작은 LO 구동 전력으로 IF 출력 주파수의 변환손실은 가능한 작고 평탄도는 일정하도록 그리고 LO 격리도가 가능한 크도록 하였다. LO 포트의 반사손실, LO 격리도, 변환손실 성능 특성간에 최적의 성능을 위하여 다이오드의 정합회로, 그리고 결합기와 정합회로 사이의 embedded 마이크로스트립 선로를 이용하여 최적화하였다. 제작된 혼합기는 6 dBm의 LO 구동 전력을 가지고 변환손실 6 dB, LO/RF 격리도 23 dB, P1 dB(input)는 3 dBm의 결과를 얻었다.

• 한국전기전자재료학회논문지
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• 제11권9호
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• pp.687-692
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• 1998

Silicon doped $Al_{0.32}Ga_{0.68}As$ were growth by molecular beam epitaxy. Electroreflectance(ER) spectra of the $E_1$ transition of Schottky barrier Au/n-$Al_{0.32}Ga_{0.68}As$ have been measured at various modulation voltage($V_{ac}$) and dc bias voltage($V_{bias}$). from the $E_1$peak, band gap energy of the $Al_{0.32}Ga_{0.68}As$ is 1.883 eV which corresponds to an Al composition of 32%. As modulation voltage($V_{bias}$) is changed, a line shape at the $E_1$transition does not change, but its amplitude varies linearly. The amplitude of $E_1$signal decrease with increasing the forward dc bias voltage($V_{bias}$), but the line shape does not change. It suggests that the low field theory rather than Franz-Keldysh oscillation is Required to interpret spectra. Also, spectra at the $E_1$transition were broadened with increasing the reverse dc bias voltage($V_{bias}$) which suggests the presence of Field-induced broadening.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.49-51
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• 2002

In this thesis, Josephson junction using high-Tc superconducting multi-layer thin film has been fabricated by on-axis RF magnetron sputtering method. And, the characterizations were performed by X-ray diffraction, SEM and the measuring system of critical current density. The physical properties of multi-layer superconducting thin films were also analyzed with the measured results. To fabricate the multi-layer superconducting thin films, the optimum partial pressure of Argon and Oxgen and the temperature of substrate were measured. Also, YBaCuO thin film was grown on MgO and $SrTiO_3$ substrates by rf-sputtering and LGO thin film of 30 A was epitaxially grown on the YBaCuO thin film as a josephson junction with the same condition. The schottky barrier at the contact surface between YBaCuO/LGO and YBaCuO/Au and the energy gap of 0.5 ${\sim}$ 0.6 mV in Nb were observed from the dI/dV-V of YBaCuO/LGO/Au/Nb and YBaCuO/Au/Nb.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.372-376
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• 2022

Since the ZnO varistor is a semiconductor device, the internal thermal distribution during the varistor operation is recognized as an important factor in the performance and deterioration of the varistor. For an optimal varistor structure design, the thermal runaway phenomenon during the varistor operation was interpreted using the Comsol 5.2 analysis program by a finite element analysis. The maximum temperature of the center measured in the cross section of the ZnO varistor was confirmed to increase as the temperature moved from the lower electrode to the center towards the upper electrode up to 572.6 K. The electrodes are thinned so that the influence of the Schottky barrier is not great. The heat gradient balance is determined to be improved when the electrode of the hybrid form is introduced. The thickness, density, pore distribution, impurity uniformity, and particle size of the ZnO varistor are required, and it is determined that the pyrolysis gradient will be improved regardless of the electrode thickness. When these results are applied to design the ZnO varistor, the optimal structure of the ZnO varistor can be obtained.

• 한국전기전자재료학회논문지
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• 제24권12호
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• pp.962-968
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• 2011

In this study, we investigated the effects of Mn dopant (0.1~3.0 at% $Mn_3O_4$ sintered at 1000$^{\circ}C$ for 1 h in air) on the bulk trap (i.e. defect) and grain boundary properties of ZnO, ZM(0.1~3.0) using admittance spectroscopy (AS), and impedance-modulus spectroscopy (IS & MS). As a result, three kinds of defect were found below the conduction band edge of ZnO as 0.09~0.14 eV (attractive coulombic center), 0.22~25 eV ($Zn^{{\cdot}{\cdot}}_i$), and 0.32~0.33 eV ($V^{\cdot}_o$). The oxygen vacancy increased with Mn doping. In ZM, an electrically single grain boundary as double Schottky barrier was formed with 0.82~1.0 eV of activation energies by IS & MS. We also find out that the barriers of grain boundary of Mn-doped ZnO (${\alpha}$-factor=0.13) were more stabilized and homogenized with temperature compared to pure ZnO.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.310-313
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• 2000

In this study, the Au/Ni and Au/Ni/Si/Ni layers prepared by electron beam evaporation were used to form ohmic contacts on p-type GaN. Before rapid thermal annealing, the current-voltage(I-V) characteristic of Au/Ni and Au/Ni/Si/Ni contact on p-type GaN film shows non-ohmic behavior. A Specific contact resistance as 3.4$\times$10$^{-4}$ Ω-$\textrm{cm}^2$ was obtained after 45$0^{\circ}C$-RTA. The Schottky barrier height reduction may be attributed to the presence of Ga-Ni and Ga-Au compounds, such as Ga$_4$Ni$_3$, Ga$_4$Ni$_3$, and GaAu$_2$ at the metal - semiconductor interface. The mixing behaviors of both Ni and Au have been studied by using X-ray photoelectron spectroscopy. In addition, X-ray diffraction measurements indicate that the Ni$_3$N, NiGa$_4$, Ni$_2$Si, and Ni$_3$Si$_2$ Compounds were formed at the metal-semiconductor interface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1418-1419
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• 2011

차세대 전력 반도체인 고전압 GaN 쇼트키 장벽 다이오드의 역방향 특성을 개선하기 위해서 열 산화공정이 제안되었다. AlGaN/GaN 에피탁시 위에 쇼트키 장벽 다이오드 구조가 제작되었으며, 쇼트키 컨택은 증착 후 $450^{\circ}C$에서 산화되었다. 열 산화공정이 메사 측벽의 AlGaN 및 GaN 표면에 $AlO_x$ 및 $GaO_x$를 형성하여 표면으로 흐르는 누설전류를 억제한다. 표면 및 GaN 버퍼를 통한 누설전류는 열 산화 공정 이후 100 ${\mu}m$-너비당 51.3 nA에서 24.9 pA로 1/2000 배 수준으로 감소하였다. 표면 산화물 형성으로 인하여 생성된 Ga-vacancy와 Al-vacancy는 acceptor로 동작하여 surface band bending을 증가시켜 쇼트키 장벽 높이를 증가시킨다. 애노드-캐소드 간격이 5 ${\mu}m$인 제작된 소자는 0.99 eV의 높은 쇼트키 장벽 높이를 획득하여, -100 V에서 0.002 A/$cm^2$의 낮은 누설전류를 확보하였다. 애노드-캐소드 간격이 5에서 10, 20, 50 ${\mu}m$로 증가되면 소자의 항복전압은 348 V에서 396, 606, 941 V로 증가되었다. 열 산화공정은 전력용 GaN 전자소자의 누설전류감소와 항복전압 증가를 위한 후처리 공정으로 적합하다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1343-1346
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• 2005

Self assembled monolayers (SAM) are generally used at the anode/organic interface to enhance the carrier injection in organic light emitting devices, which improves the electroluminescence performance of organic devices. This paper reports the use of SAM of 1-decanethiol (H-S(CH2)9CH3) at the cathode/organic interface to enhance the electron injection process for organic light emitting devices. Aluminum (Al), tris-(8-hydroxyquionoline) aluminum (Alq3), N,N'-diphenyl-N,N'-bis(3 -methylphenyl)-1,1'- diphenyl-4,4'-diamine (TPD) and indium-tin-oxide (ITO) were used as bottom cathode, an emitting layer (EML), a hole-transporting layer (HTL) and a top anode, respectively. The results of the capacitancevoltage (C-V), current density -voltage (J-V) and brightness-voltage (B-V), luminance and quantum efficiency measurements show a considerable improvement of the device performance. The dipole moment associated with the SAM layer decreases the electron schottky barrier between the Al and the organic interface, which enhances the electron injection into the organic layer from Al cathode and a considerable improvement of the device performance is observed. The turn-on voltage of the fabricated device with SAM layer was reduced by 6V, the brightness of the device was increased by 5 times and the external quantum efficiency is increased by 0.051%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.784-789
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• 2004

Bulk ZnO varistor based on Matsuoka, which varied $SiO_2$ addition has fabricated by standard ceramic process. The micro-electrode, which fabricated for investigation on degradation property of the Single Grain Boundary of ZnO varistor, has sticked by lithography semiconductor process. The values of AC degradation has measured with 150% operating voltage in varistor threshold with 120 minute in 60Hz. In here we observed V-I and V-C property in every 30minute. The operating voltage of Single Grain Boundary has shown in variable patterns in the characteristic of V-I Property. By increasing the $SiO_2$ contents, operating value has also increased and dominated on degradation proper. In EPMA analysis, we know that added $SiO_2$ was nearly distributed at the Grain Boundary. $SiO_2$ has gradually distributed in Grain Boundary condition during the process of crystal growth. It contributes to degradation depression and decision of operating voltage. We also demonstrated for using practical application and performance on distribution random loop based on V-I Properties in Single-Grain-Boundary.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.424-424
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• 2008

Dye-sensitized Solar Cell (DSC) is a new type of solar cell by using photocatalytic properties of $TiO_2$. The electric potential distribution in DSCs has played a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage(Voc) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. $TiO_2$ thin films were deposited on the FTO substrate by Nd:YAG Pulsed Laser Deposition(PLD) at room temperature and post-deposition annealing at $500^{\circ}C$ in flowing $O_2$ atmosphere for 1 hour. The structural properties of $TiO_2$ thin films have investigated by X-ray diffraction(XRD) and atomic force microscope(AFM). Thickness of $TiO_2$ thin films were controlled deference deposition time and measurement by scanning electron microscope(SEM). Then we manufactured a DSC unit cells and I-V and efficiency were tested using solar simulator.