• E2M - 전기 전자와 첨단 소재
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• 제10권7호
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• pp.659-667
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• 1997

The influence of SiO$_2$on the microstructure and electrical properties of zinc oxide varistor was investigated. Zn$_2$SiO$_4$third phase in the sintered body was found at grain boundaries, multiple grain junctions, and occasionally within ZnO grains. This phase acted as a grain growth inhibitor, which retard the grain growth of the ZnO matrix by impeding migration on the grain boundaries. As SiO$_2$ addition increases, average grain size decreased from 40.6${\mu}{\textrm}{m}$ to 26.9${\mu}{\textrm}{m}$ due to the pinning effect by Zn$_2$SiO$_4$ and drag effect by Si segregation at grain boundaries, the breakdown voltage consequently increased. When SiO$_2$ addition is increased, interface state density decreased, however, the barrier height increased by decrease of donor concentration, as a result, the nonlinear exponent increased and leakage current decreased. While, as SiO$_2$ addition increase, it was found that the apparent dielectric loss factor shows a tendency of decrease. Wholly, electrical properties of zinc oxide varistor can be said to be improved by SiO$_2$addition.

• E2M - 전기 전자와 첨단 소재
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• 제16권9호
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• pp.64.2-65
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• 2003

A 4 nm layer of ZrOx (targeted x-2) was deposited on an interfacial layer(IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 30$0^{\circ}C$. Some as-deposited layers were subjected to a post-deposition, rapid thermal annealing at $700^{\circ}C$ for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous $ZrO_2$-rich Zr silicate containing about 15% by volume of embedded $ZrO_2$ nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-$ZrO_2$(t-$ZrO_2$) and monoclinic-$ZrO_2$(m-$ZrO_2$) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interfacial layer (IL) was partitioned into an upper Si $o_2$-rich Zr silicate and the lower $SiO_{x}$. The latter was sub-toichiometric and the average oxidation state increased from Si0.86$^{＋}$ in $SiO_{0.43}$ (as-deposited) to Si1.32$^{＋}$ in $SiO_{0.66}$ (annealed). This high oxygen deficiency in $SiO_{x}$ indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor(MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of $ZrO_2$ and $SiO_2$, and the capacitance in accumulation (and therefore, EOT and kZr-O) was frequency dispersive, trends well documented in literature. This behavior is qualitatively explained in terms of the multi-layer nanostructure and nanochemistry that evolves.ves.ves.

• 한국세라믹학회지
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• 제30권8호
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• pp.615-622
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• 1993

In order to increase chemical durability of thin films in binary system B2O3-SiO2 and Al2O3-SiO2 on the slide glass by the dip-coating technique from TEOS(Tetraethyl Orthosilicate) and boric acid or aluminum nitrate, phosphoric acid(5~20mol%) was added, respectively. Corrosion of acid and alkali of samples treated with 1N, HCl, NaOH and distilled water at 10$0^{\circ}C$ for 15 minute, were measured IR transmittance and variance of transmittance at visible range. Surface structure of thin film was investigated with SEM and formation of crystal phase according to additiion of phosphoric acid was measrued with XRD. In Al2O3-SiO2 system, change of remarkable characteristic was not obtained at the addition of P2O5 but transmittance of thin film was decreased with addition of P2O5 in B2O3-SiO2 system.

• 대한전자공학회논문지SD
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• 제41권10호
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• pp.1-7
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• 2004

SOI 구조에서 형성된 MOS 트랜지스터의 장점과 strained Si에서 전자의 이동도가 향상되는 효과를 동시에 고려하기 위해 buried oxide(BOX)층과 Top Si층 사이에 Ge을 삽입하여 strained Si/relaxed SiGe/SiO₂Si 구조를 형성하고 strained Si fully depletion(FD) n-MOSFET를 제작하였다. 상부 strained Si층과 하부 SiGe층의 두께의 합을 12.8nm로 고정하고 상부 strained Si 층의 두께에 변화를 주어 두께의 변화가 electron mobility에 미치는 영향을 분석하였다. Strained Si/relaxed SiGe/SiO2/Si (strained Si/SGOI) 구조위의 FD n-MOSFET의 전자 이동도는 Si/SiO₂/Si (SOI) 구조위의 FD n-MOSFET 에 비해 30-80% 항상되었다. 상부 strained Si 층과 하부 SiGe 층의 두께의 합을 12.8nm 로 고정한 shrined Si/SGOI 구조 FD n-MOSFET에서 상부층 strained Si층의 두께가 감소하면 하부층 SiGe 층 두께 증가로 인한 Ge mole fraction이 증가함에 의해 inter-valley scattering 이 감소함에도 불구하고 n-channel 층의 전자이동도가 감소하였다. 이는 strained Si층의 두께가 감소할수록 2-fold valley에 있는 전자가 n-channel 층에 더욱더 confinement 되어 intra-valley phonon scattering 이 증가하여 전자 이동도가 감소함이 이론적으로 확인되었다.

• 한국재료학회지
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• 제21권4호
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• pp.220-224
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• 2011

Zircon has excellent thermal, chemical, and mechanical properties, but it is hard to make a dense sintered product because of dissociation during the sintering process. This study analyzes how the addition of $SiO_2$ and $Al_2O_3$ affects the mechanical properties of sintered zircon, particularly in regards to reducing the thermal dissociation and improving the mechanical properties of $ZrSiO_4$. Zircon specimens containing different amounts of $SiO_2$ and $Al_2O_3$ were prepared and sintered to observe how the mechanical properties of $ZrSiO_4$ changed according to the differing amount of $SiO_2$ and $Al_2O_3$. The $ZrSiO_4$ that was used for the starting material was ground by ball mill to an average particle size of 3 ${\mu}m$. The $SiO_2$ and $Al_2O_3$ that was used for additives were ground to an average particle size of 3 ${\mu}m$ and 0.5 ${\mu}m$, respectively. Adding $SiO_2$ resulted in transformation in the liquid phase at high temperatures, which had little effect on suppressing the thermal dissociation but enhanced the mechanical properties of $ZrSiO_4$. When $Al_2O_3$ was added, the mechanical properties of $ZrSiO_4$ decreased due to the formation of pores and abnormal grains in the microstructure of the sintered zircon.

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.91-95
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• 2012

ZnO thin films were deposited on p-type 4H-SiC substrate by pulsed laser deposition. ZnO nanowires were formed on p-type 4H-SiC substrate by furnace. Ti/Au electrodes were deposited on ZnO thin film/SiC and ZnO nanowire/SiC structures, respectively. Structural and crystallographical properties of the fabricated ZnO thin film/SiC and ZnO nanowire/SiC structures were investigated by field emission scanning electron microscope and X-ray diffraction. In this work, resistance and sensitivity of ZnO thin film/SiC gas sensor and ZnO nanowire/SiC gas sensor were measured at $300^{\circ}C$ with various CO gas concentrations (0%, 90%, 70%, and 50%). Resistance of gas sensor decreases at CO gas atmosphere. Sensitivity of ZnO nanowire/SiC gas sensor is twice as big as sensitivity of ZnO thin film/SiC gas sensor.

• 한국세라믹학회지
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• 제26권6호
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• pp.747-754
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• 1989

The effects of CuO and SiO2 on the sintered density, grain growth and magnetic properties of Sr-ferrite were investigated. The sintered density of Sr-ferrite is increased with increasing the amount of CuO or SiO2 addition. The grain of Sr-ferrite grow uniformly with the addition of CuO, so remanence increases and coercivity decreases. The addition of SiO2 increase coercivity but does not affect remanence prominently. The sintering temperature above 125$0^{\circ}C$ and SiO2 addition above 0.8wt% causes abnormal grain growth in Sr-ferrite. When CuO and SiO2 are added simultaneouly, remanence does not decrease but coercivity shows low value.

• 한국세라믹학회지
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• 제32권9호
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• pp.1033-1039
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• 1995

The current experiment has quantitatively investigated the effect of the content of CaO and SiO2 on the microstructure, density, electrical resistivity, power loss and initial permeability of manganese zinc ferrites. The density increased initially with CaO and SiO2 content and the further addition showed an adverse effect. The excess addition of CaO and SiO2 developed a discontinuous grain growth with numerous pores inside grains and lowered the electrical resistivity. The initial permeability decreased with increasing the content of SiO2. The samples with relatively low power loss showed that half of the total loss at 10$0^{\circ}C$, 100 kHz and 2000 Gauss was due to the eddy current loss.

• 한국세라믹학회지
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• 제39권3호
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• pp.233-239
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• 2002

CRT의 전면에 전자파차폐, 정전기 방지 및 저반사 효과를 위해 코팅되는 $SiO_2$/ITO (Indium Tin Oxide) 이층박막의 반사특성에 관하여 연구하였다. 실리카층 및 ITO층의 두께를 변화시키며 나타나는 반사율의 경향을 고찰하고, 이론적인 2층, 3층 저반사코팅의 디자인에 적용시켜 보았다. 입자 상으로 코팅된 ITO는 두께가 증가할수록 기공에 의해 박막의 불균일성이 증가하면서 이론적인 반사모델과의 차이가 커졌다. 실리카와 ITO의 계면에 존재하는 혼합층의 영향으로 인하여 실제측정반사율은 2층으로 디자인한 이론반사율보다 $SiO_2$/$SiO_2$+ITO/ITO의 3층으로 디자인한 반사모델에 보다 잘 적용되었다. 이론적인 저반사 디자인은 근거로 $SiO_2$/ITO 박막의 두께를 90, 65 nm로 조절한 이층막은 기준파장에서 2.5%의 반사율을 나타내었고, 가시광선 영역에서 이론반사율과 유사한 거동을 보였다.

• 한국분말재료학회지
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• 제7권1호
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• pp.35-41
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• 2000

Al2O3$.$SiC particle was prepared was prepared by the self-propagting high temperature sYthesis(SHS) process from a mixture of SiO2, Al and C powders, The fabricated Al2O3$.$SiC particle was applied to 2024Al/(Al2O3$.$SiC)pcomposite as a reinforcement. Aluminum matix composites were fabricares by the powder extrusion method using the synthesized Al2O3$.$SiC particle and commercial 2024Al powder. Theoptimum preparation conditions for Al2O3$.$SiC partticle by SHS process were described. The influence of the Al2O3$.$SiC voiume fraction on the mechanical was composite was also discussed. Despite adiabatic temperature was about 2367K, SHs reaction was completed not by itself, but by using pre-heating. Mean particle size of final particle synthesized was 0.73 ${\mu}$m and most of the particle was smaller than 2${\mu}$m. Elastic modulus and tensile strength of the composite increased with increase the volume fraction of reinforcement but, tensile strength depreciated at 30 vol% of reinforcement.