• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.496-498
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• 2005

We reported that high dielectric hafnium oxide nano-film deposited by thermal atomic layer deposition on the poly-silicon film (poly-Si). The poly -Si film was produced by plasma enhanced chemical vapor deposition and excimer laser annealing. We used the hafniu m chloride ($HfCl_4$) and water as the precursors and analyzed the hafnium oxide film by transmission electron microscope and secondary ion mass spectrometer. Hafnium oxide produced by the ALD method showed very good coverage on the rough surface of poly-Si film. While deposited with 200 cycles, these hafnium oxide films revealed a relatively smooth surface and good uniformity, but the cumulative roughness produced by the incomplete reaction was apparent when the amount of deposition cycle increased to 600 cycles.

• Nuclear Engineering and Technology
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• v.20 no.4
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• pp.233-240
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• 1988

The hafnium shroud is used to control the excess reactivity and power distribution in KMRR. The core analysis is performed by the diffusion code VENTURE using the 5 group macroscopic cross sections homogenized for an assembly. Investigated are the applicability of the diffusion calculation by homogenized cross sections to the analysis of control assembly which features unusual geometry such that hafnium shroud surrounds a multiplying medium inside. Comparative calculation is performed for the excess reactivity and power levels by the transport code TWOTRAN. The results show the acceptability of the diffusion calculation by the homogenized cross sections without significant error.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.247-253
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• 2024

The separation of zirconium and hafnium using tributyl phosphate (TBP)-Dodecane extractants in nitric acid medium was performed. Zirconium oxychloride, used as extraction feed, was obtained from the synthesis of Kalimantan zircon sand concentrate smelted using NaOH. The extraction process was carried out by dissolving chloride-based metals in nitric acid media in the presence of sodium nitrate using TBP-Dodecane as an extractant. Some of the extraction parameters carried out in this study include variations in organic phase and aqueous phase (O/A), variations in contact time, and variations in nitric acid concentration. Extraction was carried out using a mechanical shaker according to the parameter conditions. X-ray fluorescence (XRF) was used for elemental (Zr and Hf) composition analysis of the aqueous solution. The results showed that zirconium was separated from hafnium at optimum conditions with an organic/aqueous ratio of 1:5, contact time of 75 min, and an HNO₃ concentration of 7 M. The resulting separation factor of zirconium and hafnium using TBP-Dodecane was 14.4887.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1315-1318
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• 2007

Hafnium dioxide nano film as gate insulator for organic thin film transistors is prepared by atomic layer deposition. Mostly crystalline of $HfO_2$ films can be obtained with oxygen plasma and with water at relatively low temperature of $150^{\circ}C$. $HfO_2$ was deposited as a uniform rate $1.2A^{\circ}/cycle$. The morphology and performances of OTFT will be discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.211-213
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• 2008

The TFTs from ZnO semiconductor with hafnium oxide dielectrics were prepared by atomic layer deposition to characterize the electrical properties. Good electrical properties of oxide TFT was obtained with channel mobility of $2.1\;cm^2/Vs$, threshold voltage of 0 V, the subthreshold slope of 0.9 V/dec, and on to off current ratio of $10^6$.

• Transactions on Electrical and Electronic Materials
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• v.9 no.6
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• pp.247-250
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• 2008

Hafnium dioxide ($HfO_2$) thin film as a gate dielectric for organic thin film transistors is prepared by plasma enhanced atomic layer deposition (PEALD). Mostly crystalline of $HfO_2$ film can be obtained with oxygen plasma and with water at relatively low temperature of $200^{\circ}C$. $HfO_2$ was deposited as a uniform rate of $1.2\;A^{\circ}$/cycle. The pentacene TFT was prepared by thermal evaporation method with hafnium dioxide as a gate dielectric. The electrical properties of the OTFT were characterized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.116-116
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• 2007

We investigated the characteristics of the Hafnium silicate (Hf-silicate) film which is grown by ALD (atomic layer deposition). The Hf-silicate films that were annealed by the RTP. The physical and electrical properties of nitrided Hf-silicate films, incorporated by NO gas and $NH_3$ gas annealing, were investigated by XPS, TEM and I-V measurement. We confirmed the nitrogen incorporation during NO gas annealing treatment effectively enhances the thermal stability of Hf-silicate. The tendency of nitnitridation in NO gas and $NH_3$ is different. Leakage current is improved in post NO gas annealing.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.82-82
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• 2001

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.59-59
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• 2002

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.137.2-137
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• 2003