Hybrid Deep Learning Crystallographic Mapping of Polymorphic Phases in Polycrystalline Hf Zr O Thin Films.

By controlling the configuration of polymorphic phases in high-k Hf Zr O thin films, new functionalities such as persistent ferroelectricity at an extremely small scale can be exploited. To bolster the technological progress and fundamental understanding of phase stabilization (or transition) and switching behavior in the research area, efficient and reliable mapping of the crystal symmetry encompassing the whole scale of thin films is an urgent requisite. Atomic-scale observation with electron microscopy can provide decisive information for discriminating structures with similar symmetries.

High- perovskite gate oxide for modulation beyond 10 cm.

Scaling down of semiconductor devices requires high- dielectric materials to continue lowering the operating voltage of field-effect transistors (FETs) and storing sufficient charge on a smaller area. Here, we investigate the dielectric properties of epitaxial BaHfTiO (BHTO), an alloy of perovskite oxide barium hafnate (BaHfO) and barium titanate (BaTiO). We found the dielectric constant, the breakdown field, and the leakage current to be 150, 5.

High-Throughput Growth of Wafer-Scale Monolayer Transition Metal Dichalcogenide via Vertical Ostwald Ripening.

For practical device applications, monolayer transition metal dichalcogenide (TMD) films must meet key industry needs for batch processing, including the high-throughput, large-scale production of high-quality, spatially uniform materials, and reliable integration into devices. Here, high-throughput growth, completed in 12 min, of 6-inch wafer-scale monolayer MoS and WS is reported, which is directly compatible with scalable batch processing and device integration. Specifically, a pulsed metal-organic chemical vapor deposition process is developed, where periodic interruption of the precursor supply drives vertical Ostwald ripening, which prevents secondary nucleation despite high precursor concentrations.

Interfacial Layer Control by Dry Cleaning Technology for Polycrystalline and Single Crystalline Silicon Growth.

Native oxide removal prior to poly-Si contact and epitaxial growth of Si is the most critical technology to ensure process and device performances of poly-Si plugs and selective epitaxial growth (SEG) layers for DRAM, flash memory, and logic device. Recently, dry cleaning process for interfacial oxide removal has attracted a world-wide attention due to its superior passivation properties to conventional wet cleaning processes. In this study, we investigated the surface states of Si substrate during and after dry cleaning process, and the role of atomic elements including fluorine and hydrogen on the properties of subsequent deposited silicon layer using SIMS, XPS, and TEM analysis.

Liquid-solid spinodal decomposition mediated synthesis of Sb₂Se₃ nanowires and their photoelectric behavior.

The convenient synthesis of one-dimensional nanostructures of chalcogenide compounds with a visible band-gap is an essential research topic in developing next-generation photoelectronic devices. In particular, the design of a theoretically predictable synthesis process provides great flexibility and has a considerable ripple effect in nanotechnology. In this study, a novel rational growth approach is designed using the spinodal decomposition phenomenon for the synthesis of the Sb2Se3 nanowires, which is based on the thermodynamic phase diagram.

In situ atomic imaging of coalescence of Au nanoparticles on graphene: rotation and grain boundary migration.

Using in situ transmission electron microscopy, we demonstrated that gold nanoparticles are unified via "oriented attachment" assisted either by nanoparticle rotation or grain boundary migration at the attachment interface. We also observed that the combined nanoparticle changes shape with stable facet planes via surface diffusion, along with recrystallization.

Microstructural characterization of high indium-composition InXGa₁-XN epilayers grown on c-plane sapphire substrates.

The growth of high-quality indium (In)-rich In(X)Ga(1-X)N alloys is technologically important for applications to attain highly efficient green light-emitting diodes and solar cells. However, phase separation and composition modulation in In-rich In(X )Ga(1-X)N alloys are inevitable phenomena that degrade the crystal quality of In-rich In(X)Ga(1-X)N layers. Composition modulations were observed in the In-rich In(X)Ga(1-X)N layers with various In compositions.

Self-activated ultrahigh chemosensitivity of oxide thin film nanostructures for transparent sensors.

One of the top design priorities for semiconductor chemical sensors is developing simple, low-cost, sensitive and reliable sensors to be built in handheld devices. However, the need to implement heating elements in sensor devices, and the resulting high power consumption, remains a major obstacle for the realization of miniaturized and integrated chemoresistive thin film sensors based on metal oxides. Here we demonstrate structurally simple but extremely efficient all oxide chemoresistive sensors with ~90% transmittance at visible wavelengths.