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Reducing the leakage current through the gate oxide is becoming increasingly important for power consumption reduction as well as reliability in integrated circuits as the semiconducting devices continue to scale down. Here, this work reports on the high‐k dielectric SrHfO3 (SHO) based devices with ultralow leakage current density via pulsed laser deposition (PLD). The ultralow current density is achieved by optimizing the growth conditions and the associated structural properties. In the optimized conditions, the dielectric properties of the 50‐nm‐thick SHO capacitors are measured: high dielectric constant (κ = 32), low leakage current density (<10−8 A cm−2 at 2 MV cm−1), and large breakdown field (EBD > 4 MV cm−1). The surprisingly low leakage current density of SHO is ascribed to the large bandgap (≈6 eV), the large conduction band offset (CB offset > 3 eV) with respect to the semiconductor, and the low density of defect states inside the bandgap. The optimized SHO dielectric with high dielectric constant and ultralow leakage current density is proposed for future low‐power consumption devices based on Si as well as perovskite oxide semiconductors. [ABSTRACT FROM AUTHOR]

The effects of substituting the B cation in A3BO7 ceramics on their thermal physical properties were investigated by applying a large mass difference. Y3(Nb1‐xTax)O7 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized, and their structural characteristics were determined. All the fabricated Y3(Nb1‐xTax)O7 ceramics showed defective fluorite structures and glass‐like low thermal conductivity (1.18−2.04 W/m∙K at 25°C) because of the highly distorted crystal structure and significant mass difference. Substitution with Ta5+ enhanced the sintering resistance, leading to superior thermal‐insulating performance via grain boundary scattering. Furthermore, the ceramics exhibited excellent coefficients of thermal expansion, implying the promising applicability of Y3(Nb1‐xTax)O7 as new thermal barrier materials. The effect of mass difference on the thermomechanical properties of the ceramics was examined, suggesting a simple strategy for engineering the chemical composition of new thermal barrier materials. [ABSTRACT FROM AUTHOR]

Calcium magnesium alumina-silicate (CMAS) corrosion on thermal barrier coatings (TBCs) is one of the reasons for the early delamination of TBCs. In this study, the effects of CMAS on the microstructure evolution of TBCs were investigated for yttria-stabilized zirconia (YSZ), lanthanum zirconate (LZ), and composite coating with a 50:50 volume ratio of LZ and YSZ (LZ-YSZ). The LZ showed the mitigated penetration of CMAS by the formation of the reaction products produced by the high reactivity between the LZ and the molten CMAS. The LZ-YSZ showed a denser microstructure on the surface, resulting in retarding the penetration of CMAS. Therefore, the LZ-YSZ composite TBC is expected to prolong the lifetime performance and protect against further corrosive degradation of TBCs in high-temperature environments. The infiltration behavior and reaction mechanism of molten CMAS were discussed based on the microstructures after the corrosion test. [ABSTRACT FROM AUTHOR]

Crack-growth behavior in yttria-stabilized zirconia-based thermal barrier coatings (TBCs) is investigated through a cyclic thermal fatigue (CTF) test to understand TBCs' failure mechanisms. Initial cracks were introduced on the coatings' top surface and cross section using the micro-indentation technique. The results show that crack length in the surface-cracked TBCs grew parabolically with the number of cycles in the CTF test. Failure in the surface-cracked TBC was dependent on the initial crack length formed with different loading levels, suggesting the existence of a threshold surface crack length. For the cross section, the horizontal crack length increased in a similar manner as observed in the surface. By contrast, in the vertical direction, the crack did not grow very much with CTF testing. An analytical model is proposed to explain the experimentally-observed crack-growth behavior. [ABSTRACT FROM AUTHOR]

In this work, a novel thermal barrier coating (TBC) system is proposed that embeds silicon particles in coating as a crack-healing agent. The healing agent is encapsulated to avoid unintended reactions and premature oxidation. Thermal durability of the developed TBCs is evaluated through cyclic thermal fatigue and jet engine thermal shock tests. Moreover, artificial cracks are introduced into the buffer layer's cross section using a microhardness indentation method. Then, the indented TBC specimens are subject to heat treatment to investigate their crack-resisting behavior in detail. The TBC specimens with the embedded healing agents exhibit a relatively better thermal fatigue resistance than the conventional TBCs. The encapsulated healing agent protects rapid large crack openings under thermal shock conditions. Different crack-resisting behaviors and mechanisms are proposed depending on the embedding healing agents. [ABSTRACT FROM AUTHOR]