• Proceedings of the Materials Research Society of Korea Conference
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• 1993.05a
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• pp.45-45
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• 1993

• ETRI Journal
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• v.36 no.2
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• pp.214-223
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• 2014

A fully-integrated penta-band reconfigurable power amplifier (PA) is developed for handset Tx applications. The output structure of the proposed PA is composed of the fixed output matching network, power and frequency reconfigurable networks, and post-PA distribution switches. In this work, a new reconfiguration technique is proposed for a specific band requiring power and frequency reconfiguration simultaneously. The design parameters for the proposed reconfiguration are newly derived and applied to the PA. To reduce the module size, the switches of reconfigurable output networks and post-PA switches are integrated into a single IC using a $0.18{\mu}m$ silicon-on-insulator CMOS process, and a compact size of $5mm{\times}5mm$ is thus achieved. The fabricated W-CDMA PA module shows adjacent channel leakage ratios better than -39 dBc up to the rated linear power and power-added efficiencies of higher than around 38% at the maximum linear output power over all the bands. Efficiency degradation is limited to 2.5% to 3% compared to the single-band reference PA.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.111-116
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• 1998

Silicon nitride is hard and tough ceramic material. Hereby, mechanical machinability is very poor. It has also high electrical resistance. Silicon nitride of extremely high electrical resistivity becomes conductive ceramic composite by adding 30 wt% TiN. Ceramics with high electrical conductivity can be electrical discharge machined. Using by the Electrical Discharge Machining (EDM) technique. $Si_3N_4-TiN$ ceramic composite with high electrical conductivity is utilized to make metal working tool. These tool materials have severe wear problem as well as oxidation. Post HIP processing after sintering $Si_3N_4-TiN$ ceramic composites was performed. The tribological property of $Si_3N_4-TiN$ composite as a function of content of TiN was investigated in air, at room temperature. The hardness, fracture toughness, and flexural strength were compared with the wear volume. SEM observation of wear tracks can make an explanation of wear mode of $Si_3N_4-TiN$ composite.

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1859-1862
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• 2004

Europium doped yttrium vanadate ($YVO_4$:Eu) phosphor thin films were grown using a pulsed laser deposition (PLD) technique on silicon substrate. The structural characterization carried out on a series of ($YVO_4$:Eu films at post annealing temperature in the range of 550 $^{\circ}C$-1150 $^{\circ}C$ indicating that films were preferentially (200) oriented at post annealing temperature above 950 $^{\circ}C.$ Photoluminescence of thin film increased with the increase of post annealing temperature and ambient oxygen pressure though the thin film has the powder-like surface morphology at oxygen pressure above 200 mTorr. Photoluminescence decay from $^5D_1$ level of $Eu^{3+}$ show the great concentration dependency, which can be used as a good parameter to control the composition of ($YVO_4$:Eu thin film.

• Journal of the Korean Ceramic Society
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• v.44 no.7
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• pp.354-357
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• 2007

The nitriding and post-sintering behavior of silicon powder compact containing sintering additives of 2.3 wt% and 7 wt% were investigated in this study. Regardless of the liquid phase content, elongated large grains of a typical morphology evolved in the post-sintered specimens. Phase analysis revealed a complete phase transformation into ${\beta}-Si_3N_4$ in both porous systems. Oxynitride second phases (mellilite) precipitated in the latter, while those were free in the former containing less amount of liquid phase. The post-sintering condition that yielded a favorable microstructure for a filter application was achieved when the specimens were soaked at $1800^{\circ}C$ for 2 h. It was found that the thermal conductivity of porous $Si_3N_4$ ceramics is dominated by the porosity more than this factor is influenced by the addition of $Al_2O_3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.157-158
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• 2007

Effects of post-metallization anneal (PMA) on interface trap characteristics of Si-$SiO_2$ are studied. The conventional PMA method utilizes forming gas anneal, where 10% hydrogen in nitrogen atmosphere is used. A new PMA method utilizes hydrogen rich PECVD- silicon nitride $(SiN_x)$ film as a hydrogen diffusion source and a out-diffusion blocking layer. It can be shown through charge pumping current measurement that the new PMA is indeed effective to decrease Si-$SiO_2$ interface trap density.

• Korean Journal of Materials Research
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• v.19 no.3
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• pp.174-178
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• 2009

The effects of post-CMP cleaning on the chemical and galvanic corrosion of copper (Cu) and titanium (Ti) were studied in patterned silicon (Si) wafers. First, variation of the corrosion rate was investigated as a function of the concentration of citric acid that was included in both the CMP slurry and the post-CMP solution. The open circuit potential (OCP) of Cu decreased as the citric acid concentration increased. In contrast with Cu, the OCP of titanium (Ti) increased as this concentration increased. The gap in the OCP between Cu and Ti increased as citric acid concentration increased, which increased the galvanic corrosion rate between Cu and Ti. The corrosion rates of Cu showed a linear relationship with the concentrations of citric acid. Second, the effect of Triton X-$100^{(R)}$, a nonionic surfactant, in a post-CMP solution on the electrochemical characteristics of the specimens was also investigated. The OCP of Cu decreased as the surfactant concentration increased. In contrast with Cu, the OCP of Ti increased greatly as this concentration increased. Given that Triton X-$100^{(R)}$ changes its micelle structure according to its concentration in the solution, the corrosion rate of each concentration was tested.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.10
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• pp.23-30
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• 1999

We experimented on the sub 50nm patterning using E-beam lithography system. SAL601 negative E-beam resist was used for this experiment. In order to utilize the maximum ability of E-beam system, firstly, we reduced the PR thickness to 100nm, and the field size to 200 ${um}m$. Then PEB (Post Expose Bake) time/temperature, which is one of the very important factors when SAL601 is used, were reduced for minimum line width. In addition, digitizing is optimized for better results. Quantum wire and quantum dot which can be used for nanoscale memory device, such as single electron memory device, are fabricated using these developed lithography techniques.

• Current Photovoltaic Research
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• v.5 no.2
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• pp.63-67
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• 2017

Aluminum oxide ($Al_2O_3$) film deposited by atomic layer deposition (ALD) is known to supply excellent surface passivation properties on crystalline Si surface. The quality of passivation layer is important for high-efficiency silicon solar cell. double-layer structures have many advantages over single-layer materials. $Al_2O_3/SiN_X$ passivation stacks have been widely adopted for high- efficiency silicon solar cells. The first layer, $Al_2O_3$, passivates the surface, while $SiN_X$ acts as a hydrogen source that saturates silicon dangling bonds during annealing treatment. We explored the properties on passivation film of $Al_2O_3/SiN_X$ stack layer with changing the conditions. For the post annealing temperature, it was found that $500^{\circ}C$ is the most suitable temperature to improvement surface passivation.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.102-107
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• 1996

Use of a rapid thermal annealing (RTA) technique is shown to improve the properties of metal-ferroelectric BaMgF$_{4}$-silicon structures. The fluoride film was deposited in an ultra-high vacuum system at asubstrate temperature of 300$^{\circ}C$. A post-deposition annelaing was conducted for 10 seconds at 600.deg. C in a vacuum of 0.1 Torr, using a home-made RTA apparatus. The results showed that the resistivity of the ferroelectric BaMgF$_{4}$ film from a typical value of 1-2${\times}10^{11}{\Omega}{\cdot}cm$ before the annealing to about 5${\times}10^{13}{\Omega}{\cdot}cm$ and reduce the interface state density of the BaMgF$_{4}$/Si interface to about 8${\times}10^{10}cm^{2}{\cdot}$eV. Ferroelectric hysteresis measurements using a sawyer-tower circuit yielded remanent polarization and coercive field values of about 0.5$\mu$C/cm$^{2}$ and 80 kV/cm, respectively. the typical remanent polarization of the BaMgF$_{4}$ films ont he (100) and (111) oreientated silicon wafers were 0.5 - 0.6 $\mu$C/cm$^{2}$ and that of th efilms on the (110) wafers was 1.2$^{\circ}C$/cm$^{2}$.