Gallium oxide (Ga2O3), with its ultra-wide bandgap and high breakdown voltage, has emerged as a leading candidate for next-generation power devices. The performance and the Baliga figure-of-merit for power devices critically depend on breakdown voltage sustained by Schottky contact of metal with ultra-wide gap materials. However, high-quality Schottky contacts with Ga2O3 presents a significant challenge due to the presence of surface defects and formation of metal induced mid-gap defects states in Ga2O3. In this study, we investigate the electrical properties and defects at the interface between Ni metal and β-Ga₂O₃ thin films. Additionally, a 20 nm MgO thin films with various oxygen contents were deposited on β-Ga2O3 using radio-frequency magnetron sputtering and Ni/MgO/β-Ga2O3 metal-insulator-semiconductor Schottky diodes were fabricated. The frequency dependent C-V characteristic and surface-sensitive XPS depth profile is employed to study the interface of Ni/Ga2O3 and Ni/MgO/Ga2O3 Schottky barrier diodes. Our results show that the Ni/MgO/Ga₂O₃ Schottky barrier diode with 66 % O₂ in the MgO thin film during synthesis attains a barrier height of 0.87 eV. Subsequent post-metallization annealing at 300 °C in an Ar ambient for 30 min enhances the barrier height up to 1.1 eV. Also, a reduced on-resistance of 11.65 mΩ cm2 and a lower on-voltage of 0.3V was obtained after annealing in Ar. The frequency dependent C-V characteristic results show no dispersion in capacitance for the annealed sample which signify the passivation of interface defects density (Διτ) and oxide charges density (Nf) in the dielectric layer (MgO). The minimum value of Dit and Nf achieved for the sample having highest barrier height (1.1eV) are 5.41 × 1011/eV/cm2 and 2.91 × 1010/cm3, respectively. This study establishes a vigorous foundation for the expanded utilization of Ga2O3 in power electronics devices, emphasizing the vital role of interface engineering.

中文翻译：

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用于最小化高性能功率器件的 β-Ga₂O₃ 肖特基势垒二极管中捕获电荷密度的接口工程


氧化镓 （Ga2O3） 具有超宽带隙和高击穿电压，已成为下一代功率器件的主要候选者。功率器件的性能和 Baliga 品质因数在很大程度上取决于具有超宽间隙材料的金属的肖特基触点所承受的击穿电压。然而，由于 Ga2O3 中存在表面缺陷和形成金属诱导的间隙中缺陷状态，因此与 Ga2O3 的高质量肖特基接触带来了重大挑战。在本研究中，我们研究了镍金属和 β-Ga₂O₃ 薄膜之间界面的电性能和缺陷。此外，使用射频磁控溅射在 β-Ga2O3 上沉积了具有不同氧含量的 20 nm MgO 薄膜，并制备了 Ni/MgO/β-Ga2O3 金属绝缘体半导体肖特基二极管。采用频率依赖性的 C-V 特性和表面敏感的 XPS 深度剖面来研究 Ni/Ga2O3 和 Ni/MgO/Ga2O3 肖特基势垒二极管的界面。我们的结果表明，在合成过程中，MgO 薄膜中 O₂ 含量为 66 % 的 Ni/MgO/Ga₂O₃ 肖特基势垒二极管达到了 0.87 eV 的势垒高度。随后在 300 °C 的 Ar 环境中进行 30 分钟的金属化后退火，将势垒高度提高到 1.1 eV。此外，在 Ar 中退火后，导通电阻降低了 11.65 mΩ cm2，导通电压降低了 0.3V。频率相关的 C-V 特性结果表明，退火样品的电容没有色散，这意味着介电层 （MgO） 中界面缺陷密度 （Διτ） 和氧化电荷密度 （Nf） 的钝化。对于具有最高阻挡高度 （1.1eV） 的样品，达到的最小 Dit 和 Nf 值分别为 5.41 × 1011/eV/cm2 和 2.91 × 1010/cm3。 这项研究为扩大 Ga2O3 在电力电子设备中的应用奠定了有力的基础，强调了界面工程的重要作用。