Xufang Zhang

Hydrogen-terminated diamond (H-diamond) has attracted extensive attention because of its unique surface electronic structure, particularly its negative electron affinity surface and surface transfer doping effect. However, in H-diamond Schottky barrier diodes (SBDs), the interface states at the Schottky interface can strongly influence device characteristics. Therefore, clarifying the evolution of interface states under thermal conditions is essential for understanding carrier transport and thermally activated interfacial behavior. In this work, the temperature-dependent interfacial characteristics of H-diamond SBDs with a LaB₆ interlayer were systematically investigated over the temperature range of 300–500 K. Temperature-dependent capacitance-voltage (C–V) and current-voltage (I–V) measurements were used to obtain the Schottky barrier height, ideality factor, and acceptor concentration. The interface state density (D_it) was then derived from the bias-dependent ideality factor. The results reveal that D_it is on the order of 10¹³ cm^–2 eV^–1, in the energy range of approximately 0.1–0.37 eV above the valence band edge, and exhibits a clear decreasing trend as temperature increases. In addition, X-ray photoelectron spectroscopy (XPS) analysis indicates that the bonding states at the LaB₆/H-diamond interface underwent significant evolution with temperature, which is consistent with the variation trend of D_it obtained from the electrical measurements. These results elucidate the temperature-dependent evolution of the LaB₆/H-diamond interface and provide a basis for designing thermally robust Schottky contacts.

Tin-based ternary chalcogenides with low-dimensional structures are promising candidates for optoelectronic semiconductor applications. Here, SnZrS3, SnHfS3, and SnTiS3 single crystals were synthesized by chemical vapor transport. The elemental composition and crystal structure of the samples were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. UV-vis absorption measurements reveal indirect bandgaps of approximately 1.40 eV for SnZrS3 and 1.27 eV for SnHfS3, while SnTiS3 shows an optical bandgap range of 1.96–2.82 eV. Field-effect transistor measurements based on exfoliated flakes show p-type transport in SnZrS3 and SnHfS3, with field-effect mobilities of 37.3 and 6.1 cm2 V-1 s-1, respectively. SnTiS3 cannot be effectively turned off within the measured gate-voltage range, suggesting a high intrinsic carrier concentration and TiS2 conductive behavior. These results provide experimental insight into the optoelectronic properties of Sn–M–S chalcogenides and suggest their potential use in low-dimensional electronic and photodetector devices.

Diamond is an ideal semiconductor for high‐temperature, high‐voltage applications due to its wide band gap, high carrier mobility, and high thermal conductivity. Diamond Schottky barrier diodes (SBDs) have been intensively developed; however, their thermal stability has not been explored comprehensively. Considering that the diamond/metal interface is one key factor affecting the thermal stability, in this work, we employed tantalum (Ta)/oxygen‐terminated (O‐) diamond system and investigated the impact of annealing temperature (300°C, 600°C, 900°C, and 1200°C) on chemical and structural evolution of the Ta/O‐diamond interface under low‐oxygen ambient. Angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) and atomic force microscopy (AFM) were performed to examine the interface reactions and surface morphologies. Furthermore, the possible mechanism of the interface evolution under low‐oxygen ambient was discussed. This work provides insights into understanding the interface evolution and thus the thermal stability Ta/O‐diamond.

Gallium-doped hafnium oxide (HGO) exhibits excellent ferroelectricity with remarkable reliability and improved endurance characteristics. However, the requisite high-temperature annealing (>600 ^∘C) poses challenges for CMOS back-end-of-line (BEOL) integration. To achieve ferroelectric (FE) HGO at low temperatures (below 400 ^∘C), we carried out an in-depth analysis on the role of N₂ flow during rapid thermal annealing (RTA) on ferroelectricity at 400 ^∘C. Low-N₂-flow-rate annealing under reduced pressure lowers the energy barrier for stabilizing the FE orthorhombic phase (o-phase) in HGO, though at the expense of cooling efficiency. Strategic flow parameter optimization enables FE for the HGO capacitor under BEOL-compatible annealing conditions. In addition, the FE behavior of HGO films with different Ga doping concentrations was investigated. The identified Ga doping window (4.17–9.09 atomic%) redefines the phase stability criteria for 10 nm HGO FEs. The remnant polarization (2P_r) of 24.8 μC/cm² was achieved for HGO samples with 6.14 atomic% Ga processed at 400 ^∘C. Furthermore, due to the decrease in process temperature, the devices exhibit robust performance, including low leakage current and high endurance (>10⁹). This work establishes a BEOL-compatible hafnium-based FE material system through low-temperature process engineering.

Diamond, renowned for its exceptional electrical, physical, and chemical properties, including ultra-wide bandgap, superior hardness, high thermal conductivity, and unparalleled stability, serves as an ideal candidate for next-generation high-power and high-temperature electronic devices. Among diamond-based devices, Schottky barrier diodes (SBDs) have garnered significant attention due to their simple architecture and superior rectifying characteristics. This review systematically summarizes recent advances in diamond SBDs, focusing on both metal–semiconductor (MS) and metal–interlayer–semiconductor (MIS) configurations. For MS structures, we critically analyze the roles of single-layer metals (including noble metals, transition metals, and other metals) and multilayer metals in modulating Schottky barrier height (SBH) and enhancing thermal stability. However, the presence of interface-related issues such as high densities of surface states and Fermi level pinning often leads to poor control of the SBH, limiting device performance and reliability. To address these challenges and achieve high-quality metal/diamond interfaces, researchers have proposed various interface engineering strategies. In particular, the introduction of interfacial layers in MIS structures has emerged as a promising approach. For MIS architectures, functional interlayers—including high-k materials (Al₂O₃, HfO₂, SnO₂) and low-work-function materials (LaB₆, CeB₆)—are evaluated for their efficacy in interface passivation, barrier modulation, and electric field control. Terminal engineering strategies, such as field-plate designs and surface termination treatments, are also highlighted for their role in improving breakdown voltage. Furthermore, we emphasize the limitations in current parameter extraction from current–voltage (I–V) properties and call for a unified new method to accurately determine SBH. This comprehensive analysis provides critical insights into interface engineering strategies and evaluation protocols for high-performance diamond SBDs, paving the way for their reliable deployment in extreme conditions.