We have studied the optical band and defect transitions of ScN, a group IIIB transition metal nitride semiconductor with electronic and optoelectronic applications. Recent works have focused on the degenerate nature of ScN by substitutional impurities ON and FN, which shift the direct (X–X) gap transition to higher energies via the Burstein–Moss effect. We used cathodoluminescence spectroscopy (CLS) to observe optical signatures of both the midgap VN precursor to ON doping as well as above the direct (X–X) bandgap corresponding to band-to-band transitions from four separate conduction bands near the Γ point with the valence band minimum, in agreement with the calculated band structure diagrams. Thin film ScN grown by reactive magnetron sputtering displays mild degenerate doping by substitutional oxygen as indicated by elevated (X–X) transition energies and the presence of Sc–O bonding determined via x-ray photoelectron spectroscopy (XPS), while ScN grown by physical vapor transport exhibited the intrinsic, non-degenerate (X–X) bandgap predicted by theory. CLS reveals a sharp, sub-bandgap emission at 1.26 eV for sputter grown ScN on GaN, which we attribute to nitrogen vacancies (VN) based on surface sensitive CLS and XPS chemical trends. This finding is in strong agreement with theoretical calculations for VN predicting the formation of a defect energy level within the gap.

中文翻译：

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ScN 的阴极发光和 X 射线光电子能谱：掺杂剂、缺陷和能带结构

我们研究了 ScN 的光带和缺陷跃迁，ScN 是一种具有电子和光电应用的 IIIB 族过渡金属氮化物半导体。最近的工作集中在 ScN 通过替代杂质 ON 和 FN 的简并性质，这通过 Burstein-Moss 效应将直接 (X-X) 间隙转变转移到更高的能量。我们使用阴极发光光谱 (CLS) 来观察中带隙 VN 前驱体对 ON 掺杂以及直接 (X-X) 带隙上方的光学特征，这些带隙对应于 Γ 点附近四个独立导带的带间跃迁价带最小值，与计算的能带结构图一致。通过反应磁控溅射生长的薄膜 ScN 显示出由置换氧引起的轻度简并掺杂，如 (X-X) 跃迁能升高和通过 X 射线光电子能谱 (XPS) 确定的 Sc-O 键的存在所示，而通过物理生长的 ScN蒸汽传输表现出理论预测的固有的非简并 (X-X) 带隙。CLS 揭示了在 GaN 上溅射生长的 ScN 的 1.26 eV 的尖锐亚带隙发射，我们将其归因于基于表面敏感的 CLS 和 XPS 化学趋势的氮空位 (VN)。这一发现与预测间隙内缺陷能级形成的 VN 的理论计算非常一致。理论预测的非简并 (X-X) 带隙。CLS 揭示了在 GaN 上溅射生长的 ScN 的 1.26 eV 的尖锐亚带隙发射，我们将其归因于基于表面敏感的 CLS 和 XPS 化学趋势的氮空位 (VN)。这一发现与预测间隙内缺陷能级形成的 VN 的理论计算非常一致。理论预测的非简并 (X-X) 带隙。CLS 揭示了在 GaN 上溅射生长的 ScN 的 1.26 eV 的尖锐亚带隙发射，我们将其归因于基于表面敏感的 CLS 和 XPS 化学趋势的氮空位 (VN)。这一发现与预测间隙内缺陷能级形成的 VN 的理论计算非常一致。