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We investigated the electrical characterization and defect properties of Ga2O3/SiC hetero-structured Schottky diodes manufactured by mist chemical vapor deposition. For a comprehensive analysis of the impact of post deposition annealing with nitrogen (N2), various characterization techniques were employed, including current density-voltage (J-V), capacitance-voltage (1/C2-V), atomic force microscopy (AFM), and deep level transient spectroscopy (DLTS). The on/off ratios, barrier heights and ideality factors of non-annealed and N2-annealed diodes were investigated using J-V characteristics. It was confirmed that electrical characteristics were improved in the N2-annealed diode. By analyses of 1/C2-V characteristics, the built-in voltage (Vbi) and near surface to bulk carrier concentrations were obtained. Surface topography and roughness, observed through AFM, indicated enhanced crystal quality of the N2-annealed diode. Deep level trap parameters and possible distributions of each trap were extracted from DLTS spectra and Arrhenius plots. The N2-annealing process increased the defects originating from extrinsic impurities at 0.226 eV, while decreasing the traps associated with oxygen vacancies at 0.950 eV and 1.257 eV, which can act as recombination centers. This suggests that the N2-annealing process reduces oxygen vacancies by nitrogen atoms occupying the vacancy sites, leading to a more ordered crystal lattice. Consequently, electrical conductivity, carrier mobility, and overall device performance could be enhanced. [ABSTRACT FROM AUTHOR]

This study investigated the impact of the post-deposition annealing (PDA) process on the material and electrical properties of copper oxide (Cu2O) and nickel oxide (NiO) thin films deposited on a silicon carbide (SiC) substrate. Through radiofrequency (RF) sputtering, these films were subjected to PDA in a nitrogen (N2) and oxygen (O2) gas environment. Remarkably, the Cu2O films resisted phase transition following the N2 PDA process but exhibited a transition to cupric oxide (CuO) after undergoing the O2 PDA process. The symmetry of Cu 2p in the as-deposited Cu2O film was excellent; however, the phase-transformed CuO films exhibited an increase in binding energy and the emergence of satellite peaks. The Ni 2p exhibited various defects, such as nickel vacancies (VNi) and interstitial oxygen (Oi), in response to the different PDA atmospheres. The rectification ratios of the N2-annealed Cu2O and NiO devices were determined as 1.50 × 107 and 4.01 × 106, respectively, signifying a substantial enhancement by a factor of approximately 789 for the Cu2O/SiC device and 124 for the NiO/SiC device relative to their non-annealed counterparts. The findings of this study indicate that meticulous control of deposition for potential p-type materials such as Cu2O and NiO can significantly improve the performance in applications involving high-throughput and low-cost electronics. [ABSTRACT FROM AUTHOR]

We investigated morphological properties of vertical heterojunction Schottky diodes based on (Al0.1Ga0.9)2O3/4H-SiC (AGO) thin films and analyzed the effect of post-annealing on their temperature-dependent electrical characteristics over the temperature range of 298 to 498 K. The AGO films were deposited using radio frequency sputtering and analyzed the as-deposited and N2-annealed films at 950 °C in a nitrogen atmosphere. The N2-annealed sample exhibited an estimated grain size of 63.2 nm compared to an average grain size of 43.6 nm in the as-deposited samples. As temperature increased, the barrier height (Φb) exhibited an upward trend, while the ideality factor (n) showed a declining trend. The calculated values of Φb and n in the as-deposited sample varied from 1.11 eV and 2.76 at 298 K to 1.47 eV and 1.37 at 498 K. The Schottky diode’s I–V characteristics, which vary with temperature, exhibited a Gaussian distribution. The temperature-dependent electrical characteristics of the Schottky diodes have shown a Gaussian distribution, yielding a mean barrier height of 2.08 eV and a standard deviation of 0.22 V for the as-deposited sample. In contrast, the N2-annealed sample’s mean barrier height was 1.16 eV, with a standard deviation of 0.13 V. [ABSTRACT FROM AUTHOR]

Ga2O3/4H-SiC heterojunction diodes were fabricated by depositing Ga2O3 thin films on 4H-SiC substrates using aerosol deposition (AD). X-ray diffraction (XRD) analysis showed that all Ga2O3 peaks increased with increasing oxide thickness. Scanning electron microscopy (SEM) was performed to confirm grain size and deposited area. The I–V curves showed relevance between oxide thickness and electrical properties. For these thin films, the 1200 nm sample shows low Vth among them. It was confirmed that the Ron,sp value and the On-state current increased as the oxide thickness increased. [ABSTRACT FROM AUTHOR]

High-k oxide materials for metal–oxide–semiconductor field-effect transistors and metal–oxide–semiconductor (MOS) structure on SiC have been explored to enhance SiC-based device performance. In our experiments, the MOS capacitors with a high-k barium titanate (BaTiO3) insulating layer were fabricated using the aerosol deposition (AD) method, and post-deposition annealed in O2 atmospheres. We examined the effects of post-deposition annealing on the BaTiO3 films and their impact on the surface and electrical characteristics of MOS capacitors. The crystallinity and surface morphologies of the BaTiO3 films were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy. We conducted the electrical analysis through current–voltage and capacitance–voltage (C–V) measurements. The post-deposition annealing process effectively reduced the gate leakage current of BaTiO3/4H-SiC and elevated the rectification ratio from 9.12 × 108 to 1.61 × 109. C–V characteristics were measured at 1 MHz to investigate the oxide defect charges inside the MOS capacitors. Near-interface trap density ( N it ) decreased from 9.10 × 1011 to 5.53 × 1011 cm−2 due to post-annealing, which diminished flat band voltage hysteresis. Fixed oxide charge density ( Q f ) also diminished from 4.00 × 1011 to 3.58 × 1011 cm−2, and the oxygen vacancies were compensated by the oxygen atoms introduced from the O2 during the post-deposition annealing. Our findings suggest that the post-deposition annealed process significantly influences surface and electrical properties during BaTiO3 thin film deposition using AD. [ABSTRACT FROM AUTHOR]

The high breakdown electric field, n-type doping capability, availability of high-quality substrates, and high Baliga's figure of merit of Ga2O3 demonstrate its potential as a next-generation power semiconductor material. However, the thermal conductivity of Ga2O3 is lower than that of other wide-bandgap materials, resulting in the degradation of the electrical performance and reduced reliability of devices. The heterostructure formation on substrates with high thermal conductivity has been noted to facilitate heat dissipation in devices. In this work, Ga2O3 thin films with an Al2O3 interlayer were deposited on SiC substrates by radio frequency sputtering. Post-deposition annealing was performed at 900 °C for 1 h to crystallize the Ga2O3 thin films. The Auger electron spectroscopy depth profiles revealed the interdiffusion of the Ga and Al atoms at the Ga2O3/Al2O3 interface after annealing. The X-ray diffraction (XRD) results displayed improved crystallinity after annealing and adding the Al2O3 interlayer. The crystallite size increased from 5.72 to 8.09 nm as calculated by the Scherrer equation using the full width at half maximum (FWHM). The carrier mobility was enhanced from 5.31 to 28.39 cm2 V−1 s−1 in the annealed Ga2O3 thin films on Al2O3/SiC. The transfer and output characteristics of the Ga2O3/SiC and Ga2O3/Al2O3/SiC back-gate transistors reflect the trend of the XRD and Hall measurement results. Therefore, this work demonstrated that the physical and electrical properties of the Ga2O3/SiC back-gate transistors can be improved by post-deposition annealing and the introduction of an Al2O3 interlayer. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDCs), as next-generation two-dimensional materials, have gained considerable attention in energy storage applications through the incorporation of functional materials. In this work, we investigated NbSe2 TMDCs possessing metallic properties through the exfoliation of mono/few layered nanosheets and their subsequent incorporation with polypyrrole, a conducting polymer. The charge–charge interaction between the positively charged pyrrole and negatively charged NbSe2 nanosheets was facilitated through a chemical incorporation method, resulting in NbSe2@polypyrrole hybrid nanocomposites where the pyrrole molecules polymerized along the surface of NbSe2 nanosheets. The synergistic effect observed in NbSe2@polypyrrole hybrid nanocomposites demonstrated high capacity for lithium storage (955 mA h g−1) with excellent cycling stability (>100 cycles) and rate performance (4 A g−1), surpassing the performance of pristine NbSe2 or polypyrrole electrodes. In particular, the NbSe2@polypyrrole hybrid nanocomposite exhibited 361 mA h g−1 discharge capacity retention within a charge/discharge time of less than 6 minutes, which is comparable with the capacity of conventional graphite anodes. Our hybrid approach utilizing TMDCs and carbon structures could provide significant insight for the utilization of novel TMDC materials in energy storage applications. [ABSTRACT FROM AUTHOR]