In this study, Y₂O₃ thin films were deposited on Si(100) wafers using an RF sputtering system with a Y₂O₃ target. The Y₂O₃ thin film was confirmed to have a thickness of 227 nm/min and a uniformity of 1.34% at a substrate temperature of 400℃. All samples were annealed at 600, 800, and 1,000℃ for 1 hour in an O₂ gas atmosphere using the furnace. The analysis of the XRD patterns revealed that the peak intensity increased with annealing up to 800℃, but decreased when the annealing temperature was raised to 1,000℃. The XPS analysis confirmed the onset of crystallization at 800℃, in agreement with the trends observed in the XRD results. According to the AFM results, the surface became slightly smoother after heat treatment, as indicated by a reduced RMS roughness of approximately 1.792 nm.

The ferroelectricity in Hf_0.5Zr_0.5O₂ (HZO) thin films is one of the most interesting topics for next-generation nonvolatile memory applications. It is known that a crystallization process is required at a temperature of 400℃ or higher to form an orthorhombic phase that results in the ferroelectric properties of the HZO film. However, to realize the integration of ferroelectric HZO films in the back-end-of-line, it is necessary to reduce the annealing temperature below 400℃. This study aims to comprehensively analyze the ferroelectric properties according to the annealing temperature (350-500℃) and time (1-5 h) using a furnace as a crystallization method for HZO films. As a result, the ferroelectric behaviors of the HZO films were achieved at a temperature of 400℃ or higher regardless of the annealing time. At the annealing temperature of 350℃, the ferroelectric properties appeared only when the annealing time was sufficiently increased (4 h or more). Based on these results, it was experimentally confirmed that the optimization of the annealing temperature and time is very important for the ferroelectric phase crystallization of HZO films and the improvement of their ferroelectric properties.

This study investigated the microstructure and piezoelectric properties of lead-free 0.74(Bi_1/2Na_1/2)TiO3-0.26SrTiO₃ (BNST26) piezoelectric ceramics sintered using a microwave furnace. For comparison, specimens were also prepared using a conventional furnace sintering (CFS). Average grain sizes of 2.4 μm and 3.2 μm were obtained in the sample sintered at 1,100℃ for 5 min using microwave sintering (MWS) and at 1,175℃ for 2 h using CFS, respectively. To quantify the changes in the microstructures and electrical properties according to the sintering conditions, the polarization hysteresis, bipolar and unipolar strain curves, and temperature dependence of permittivity were evaluated. As a result, it was determined that the Pmax (maximum polarization), Pr (remanent polarization) and Smax (maximum strain) values tend to increase with the average grain size. Based on these results, it is concluded that the MWS method can produce lead-free ceramics with superior performance in a relatively short time compared to the conventional CFS method.

In order to fabricate high-quality SiC substrates for power electronic devices, various single crystal growing methods were prepared. These include the physical vapor transport (PVT) and top seeded solution growth (TSSG) methods. All the suggested SiC growth methods generally use induction-heating furnaces. The temperature distribution in this system can be easily adjusted by changing the hot-zone design. Moreover, precise temperature control in the induction-heating furnace is favorably required to grow a high-quality crystal. Therefore, in this study, we analyzed the heat transfer in these furnaces to grow SiC crystals. As the growth temperature of SiC crystals is very high, we evaluated the effect of radiation heat transfer on the temperature distribution in induction-heating furnaces. Based on our simulation results, a heat transfer strategy that controls the radiation heat transfer was suggested to obtain the optimal temperature distribution in the PVT and TSSG methods.

ZnO nanostructures were developed on a Si (100) substrate from powder mixture of ZnO and 5 mol% Pd (ZP-5) as reactants by × sccm oxygen pressures(x= 0, 10, 20, 40). DTA (differential thermal analysis) result shows the Pd(5 mol%)+ZnO mixtured powder(PZ-5) is easily evaporated than pure ZnO powder. The PZ-5 mixtured powder was characterized by DTA to determine the thermal decomposition which was found to be at 800℃, 1,100℃. Weight loss(%) and ICP (inductively coupled plasma) analysis reveal that Zn vaporization is decreased by increased oxygen pressures from the PZ-5 at 1,100℃ for 30 mins. Needle-like ZnO nanostructures array developed from 10 sccm oxygen pressure, was well aligned vertically on the Si substrate at 1,100℃ for 30 mins. The lengths of the Needle-like ZnO nanostructures is about 2 μm with diameters of about 65 nm. The developed ZnO nanostructures exhibited growth direction along [001] with defect-free high crystallinity. It is considered that Zn vaporization is responsible for the growth of Needle-like ZnO nanostructures by controlling the oxygen pressures. The photoluminescence spectra of ZnO nanostructures exhibited stronger 376.7 nm NBE (near band-edge emission) peak and 529.3 nm DLE (deep level energy) peak.