• 한국전기전자재료학회논문지
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• 제23권8호
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• pp.587-592
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• 2010

We have fabricated schottky barrier diode (SBDs) using polar (c-plane) and non polar (a-, m-plane) n-type 6H-SiC wafers. Ni/SiC ohmic contact was accomplished on the backside of the SiC wafers by thermal evaporation and annealed for 20minutes at $950^{\circ}C$ in mixture gas ($N_2$ 90% + $H_2$ balanced). The specific contact resistance was $3.6{\times}10^{-4}{\Omega}cm^2$ after annealing at $950^{\circ}C$. The XRD results of the alloyed contact layer show that formation of $NiSi_2$ layer might be responsible for the ohmic contact. The active rectifying electrode was formed by the same thermal evaporation of Ni thin film on topside of the SiC wafers and annealed for 5 minutes at $500^{\circ}C$ in mixture gas ($N_2$ 90% + $H_2$ balanced). The electrical properties of SBDs have been characterized by means of I-V and C-V curves. The forward voltage drop is about 0.95 V, 0.8 V and 0.8 V for c-, a- and m-plane SiC SBDs respectively. The ideality factor (${\eta}$) of all SBDs have been calculated from log(I)-V plot. The values of ideality factor were 1.46, 1.46 and 1.61 for c-, a- and m-plane SiC SBDs, respectively. The schottky barrier height (SBH) of all SBDs have been calculated from C-V curve. The values of SBH were 1.37 eV, 1.09 eV and 1.02 eV for c-, a- and m-plane SiC SBDs, respectively.

• 한국결정성장학회지
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• 제4권4호
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• pp.378-387
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• 1994

선행연구[1] 즉, $Ti0_2/Pb/TiO_2(900{\AA}/900{\AA}/900{\AA}/)$ 3층구조박막으로부터 열확산에 의해 상형성이 가능하였던 $PbTiO_3$ 박막의 특성을 개선하기 위하여 스퍼터링법을 이용하여 Si기판위에 각 요소층의 두께를 $200~300 {\AA}$으로 얇게하고 적층수를 3,5,7,9,11층$(TiO_2/Pb/.../Tio_2)$으로 변화시켜가며 다층구조박막을 형성한 후 이를 RTA 처리하여 $PbTiO_3$ 박막을 제조하였다. 그 결과 $500^{\circ}C$ 이상에서 단일상의 $PbTiO_3$가 형성되었다. 또한 요소층의 두께를 얇게하고 적층수를 늘려서 열처리한 결과 Pb-silicate 및 void 생성이 억제되어 우수한 계면상태를 유지하였으며 조성도 보다 균일해지는 양상을 나타내었다. $PbTiO_3$ 박막의 MiM구조에 C-V 특성으로부터 측정된 유전상수는 열처리 조건에 따른 경향을 나타내지 않았으나 적층수가 많아져 박막의 두께가 증가 할수록 유전상수가 증가하였다. MIS 구조의 $PbTiO_3$ 박막의 I-V 특성 측정 결과 절연파괴강도는 최고 150kV/cm이었다.

• 한국표면공학회지
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• 제29권6호
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• pp.766-772
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• 1996

Undoped $SnO_x$ thin films were deposited on Si(100) substrate by using reactive ioassisted deposition technique (R-IAD). In order to investigate the effect of initial oxygen content and heat treatment on the oxidation state and crystalline structure of tin oxide films, $SnO_x$ thin films were post-annealed at 400~$600^{\circ}C$ for 1 hr. in a vacuum ~$5 \times 10^{-3}$ -3/ Torr or were directly deposited on the substrate of $400^{\circ}C$ and the relative arrival ration ($Gamma$) of oxygen ion to Sn metal varied from 0.025 to 0.1, i.e., average impinging energy ($E_a$) form 25 to 100 eV/atom. As $E_a$ increased, the composition ratio of $N_ON{sn}$ changed from 1.25 to 1.93 in post-annealing, treatment and 1.21 to 1.87 in in-situ substrate heating. In case of post-annealing, the oxidation from SnO to $SnO_2$ was closely related to initial oxygen contents and post-annealing temperature, and the perfect oxidation of $SnO_2$ in the film was obtained at higher than $E_a$=75 eV/atom and $600^{\circ}C$. The temperature for perfect oxidation of $SnO_2$ was reduced as low as $400^{\circ}C$ through in-situ substrate heating. The variation of the chemical state of $SnO_x$ thin films with changing $E_a$'s and heating method were also observed by Auger electron spectroscopy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.5-5
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• 2009

Thin-film-transistors (TFTs) that can be prepared at low temperatures have attracted much attention because of the great potential for transparent and flexible electronics. One of the mainstreams in this field is the use of organic semiconductors such as pentacene. But device performance of the organic TFTs is still limited due to low field-effect mobility and rapid degradation after exposing to air. Alternative approach is the use of amorphous oxide semiconductors as a channel. Amorphous oxide semiconductors (AOSs) based TFTs showed the fast technological development, because AOS films can be fabricated at room temperature and exhibit the possibility in application like flexible display, electronic paper, and larges solar cells. Among the various AOSs, a-IGZO has lots of advantages because it has high channel mobility, uniform surface roughness and good transparency. [1] The high mobility is attributed to the overlap of spherical s-orbital of the heavy post-transition metal cations. This study demonstrated the effect of the variation in channel thickness from 30nm to 200nm on the TFT device performance. When the thickness was increased, turn-on voltage and subthreshold swing was decreased. The a-IGZO channels and source/drain metals were deposited with shadow mask. The a-IGZO channel layer was deposited on $SiO_2$/p-Si substrates by RF magnetron sputtering, where RF power is 150W. And working pressure is 3m Torr, at $O_2/Ar$ (2/28 sccm) atmosphere. The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. Finally, Al (150nm) as a gate metal was thermal-evaporated. TFT devices were heat-treated in a furnace at 250 $^{\circ}C$ and nitrogen atmosphere for 1hour. The electrical properties of the TFTs were measured using a probe-station. The TFT with channel thickness of 150nm exhibits a good subthreshold swing (SS) of 0.72 V/decade and on-off ratio of $1{\times}10^8$. The field effect mobility and threshold voltage were evaluated as 7.2 and 8 V, respectively.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1491-1494
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• 2008

A novel platinum aminoalkoxide complex, Pt$(dmamp)_2$ has been prepared by the reaction of cis-$(py)_2PtI_2$ with two equivalents of Na(dmamp) (dmamp = 1-dimethylamino-2-methyl-2-propanolate). Single-crystal X-ray crystallographic analysis shows that the Pt(dmamp)2 complex keeps a square planar geometry with each two nitrogen atoms and two oxygen atoms having trans configuration. Platinum films have been deposited on TaN/ Ta/Si substrates by metal organic chemical vapor deposition (MOCVD) using Pt$(dmamp)_2$. As-deposited platinum thin films did not contain any appreciable amounts of impurities except a little carbon. As the deposition temperature was increased, the films resistivity and deposition rate increased. The electrical resistivity (13.6 $\mu\Omega$cm) of Pt film deposited at 400 ${^{\circ}C}$ is a little higher than the bulk value (10.5 $\mu\Omega$cm) at 293 K. The chemical composition, crystalline structure, and morphology of the deposited films were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, and atomic force microscopy.

• 한국전기전자재료학회논문지
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• 제33권5호
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• pp.427-431
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• 2020

In this research, we evaluated the electrical properties of polycrystalline-gallium-oxIde (Ga₂O₃) thin films grown by mist-CVD. A 500~800 nm-thick Ga₂O₃ film was used as a channel in a fabricated bottom-gate MOSFET device. The phase stability of the β-phase Ga₂O₃ layer was enhanced by an annealing treatment. A Ti/Al metal stack served as source and drain electrodes. Maximum drain current (I_D) exceeded 1 mA at a drain voltage (V_D) of 20 V. Electron mobility of the β-Ga₂O₃ channel was determined from maximum transconductance (g_m), as approximately, 1.39 ㎠/Vs. Reasonable device characteristics were demonstrated, from measurement of drain current-gate voltage, for mist-CVD-grown Ga₂O₃ thin films.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1352-1354
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• 1998

$LiNbO_3$ transistor showed relatively stable characteristic, low interface trap density, and large remanent polarization. This paper reports ferroelectric $LiNbO_3$ thin films grown directly on p-type Si(100) substrates by 13.56 MHz rf magnetron sputtering system for FRAM applications. To take advantage of low temperature requirement for growing films, we deposited $LiNbO_3$ films lower than $300 ^{\circ}C$. RTA(Rapid Thermal Anneal) treatment was performed for as-deposited films in an oxygen atmosphere at $600^{\circ}C$ for 60 sec. We learned from X-ray diffraction that the RTA annealed films were changed from amorphous to poly-crystalline $LiNbO_3$ which exhibited (012), (015), and (022) orientations. The I-V characteristics of $LiNbO_3$ films before and after anneal treatment showed that RTA improved the leakage current of films. The leakage current density of films decreased from $10^{-5}$ to $10^{-7} A/cm^2$ at room temperature measurement. Breakdown electric field of the films exhibited higher than 500 kV/cm. The C-V curves showed the clockwise hysteresis represents ferroelectric switching characteristics. From C-V curves, we calculated dielectric constant of thin film $LiNbO_3$ as 27.5 which is close to that of bulk value.

• 센서학회지
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• 제7권3호
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• pp.154-162
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• 1998

필라멘트 모양의 백금 박막 히터 및 Bi-Sb 박막 열전퇴(thermopile)의 고온 접합부를 열차단막 역할을 하는 $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$ 다이아프램위에, 열전퇴의 저온 접합부를 방열판 역할을 하는 실리콘 기판에 의해 지지되는 유전체 멤버레인위에 각각 형성시켜, 열감도가 높고 교류-직류 변환오차가 작은 평면형 Bi-Sb 다중접합 열전변환기를 제작하고, fast reversed dc 방법으로 변환기의 교류-직류 변환특성을 측정하였다. 단일 bifilar 히터로 제작된 변환기의 열감도는 공기 및 진공중에서 각각 약 10.1 mV/mW 및 14.8 mV/mW였고, 2중 bifilar 히터로 제작된 변환기의 열감도는 안쪽 및 바깥쪽에 있는 히터를 입력으로 하였을 강우 공기 및 진공중에서 각각 약 5.1 mV/mW 및 7.6 mV/mW 그리고 각각 약 5.3 mV/mW 및 7.8 mV/mW로서, 기체에 의한 열손실이 거의 없는 진공중에서의 열감도가 공기중에서의 열감도보다 더 높게 나타났다. 10 kHz이하의 주파수 범위에서 변환기의 교류-직류 전압 및 전류 변환오차 범위는, 단일 bifilar 히터로 제작된 경우 공기중에서 각각 약 ${\pm}1.80\;ppm$ 및 ${\pm}0.58\;ppm$이었고, 2중 bifilar 히터로 제작된 경우 안쪽 및 바깥쪽 히터를 입력으로 하였을 때 공기중에서 각각 약 ${\pm}0.63\;ppm$ 및 ${\pm}0.25\;ppm$ 그리고 각각 약 ${\pm}0.53\;ppm$ 및 ${\pm}0.27\;ppm$였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.145-145
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• 2008

High-k materials have been paid much more attention for their characteristics with high permittivity to reduce the leakage current through the scaled gate oxide. Among the high-k materials, $ZrO_2$ is one of the most attractive ones combing such favorable properties as a high dielectric constant (k= 20 ~ 25), wide band gap (5 ~ 7 eV) as well as a close thermal expansion coefficient with Si that results in good thermal stability of the $ZrO_2$/Si structure. During the etching process, plasma etching has been widely used to define fine-line patterns, selectively remove materials over topography, planarize surfaces, and trip photoresist. About the high-k materials etching, the relation between the etch characteristics of high-k dielectric materials and plasma properties is required to be studied more to match standard processing procedure with low damaged removal process. Among several etching techniques, we chose the inductively coupled plasma (ICP) for high-density plasma, easy control of ion energy and flux, low ownership and simple structure. And the $BCl_3$ was included in the gas due to the effective extraction of oxygen in the form of $BCl_xO_y$ compounds. During the etching process, the wafer surface temperature is an important parameter, until now, there is less study on temperature parameter. In this study, the etch mechanism of $ZrO_2$ thin film was investigated in function of $Cl_2$ addition to $BCl_3$/Ar gas mixture ratio, RF power and DC-bias power based on substrate temperature increased from $10^{\circ}C$ to $80^{\circ}C$. The variations of relative volume densities for the particles were measured with optical emission spectroscopy (OES). The surface imagination was measured by scanning emission spectroscope (SEM). The chemical state of film was investigated using energy dispersive X-ray (EDX).

• 전자공학회논문지
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• 제49권10호
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• pp.111-121
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• 2012

본 연구에서는 $0.5{\mu}m$ 급 다결정 실리콘 박막 트랜지스터를 제작하고 이를 최적화 했다. 실험 결과, 비정질 실리콘을 증착 후 저온 어닐링을 통해 보다 큰 grain 크기를 가지는 active 영역을 형성하는 것이 소자의 SS(Subthreshold Swing), DIBL(Drain Induced Barrier Lowering), 그리고 on-current의 성능 향상을 가져온다는 것을 확인 할 수 있었다. 또한 이를 바탕으로 SONOS 플래시 메모리를 제작하였으며 그 특성을 분석했다. 게이트로부터 전자의 back tunneling 현상을 억제함과 동시에 제작한 소자가 원활한 program/erase 동작을 하기 위해서는 O/N/O 두께의 최적화가 필요하다. 따라서 시뮬레이션을 통해 이를 분석하고 O/N/O 두께를 최적화 하여 SONOS 플래시 메모리의 특성을 개선하였다. 제작한 소자는 2.24 V의 threshold voltage($V_{th}$) memory window를 보였으며 메모리 동작을 잘 하는 것을 확인 할 수 있었다.