The optical properties of single ion tracks have been studied in ZnO implanted with Ge by combining depth-resolved hyperspectral cathodoluminescence (CL) and photoluminescence (PL) spectroscopy techniques. The results indicate that ZnO is susceptible to implantation doses as low as 10⁸ to 10⁹ cm⁻². We demonstrate that the intensity ratio of ionized and neutral donor bound exciton emissions [D⁺X/D⁰X] can be used as a tracer for a local band bending both at the surface as well as in the crystal bulk along the ion tracks. The hyperspectral CL imaging performed at 80 K with 50 nm resolution over the regions with single ion tracks permitted direct assessment of the minority carrier diffusion length. The radii of distortion and space charge surrounding single ion tracks were estimated from the 2D distributions of defect-related green emission (GE) and excitonic D⁺X emission, both normalized with regard to neutral D⁰X emission, i.e., from the [GE/D⁰X] and [D⁺X/D⁰X] ratio maps. Our results indicate that single ion tracks in ZnO can be resolved up to ion doses of the order of 5 × 10⁹ cm⁻², in which defect aggregation along the extended defects obstructs signatures of individual tracks.

中文翻译：

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ZnO中单离子轨道的光学特征

通过结合深度分辨高光谱阴极发光 (CL) 和光致发光 (PL) 光谱技术，在注入 Ge 的 ZnO 中研究了单离子轨道的光学特性。结果表明ZnO对低至10 ⁸至10 ⁹ cm ^-2的注入剂量敏感。我们证明了电离和中性供体结合激子发射的强度比 [D ⁺ X/D ⁰X] 可用作沿离子轨道在表面以及晶体块中弯曲的局部带的示踪剂。在具有单离子轨迹的区域上以 80 K 和 50 nm 分辨率进行的高光谱 CL 成像允许直接评估少数载流子扩散长度。^{从缺陷相关绿色发射 (GE) 和激子 D +} X 发射的 2D 分布估计单个离子轨道周围的畸变半径和空间电荷，两者均针对中性 D ⁰ X 发射进行归一化，即来自 [GE /D ⁰ X] 和 [D ⁺ X/D ⁰ X] 比率图。我们的结果表明，ZnO 中的单个离子轨迹可以分辨高达 5 × 10 数量级的离子剂量⁹ cm ^-2，其中沿扩展缺陷的缺陷聚集阻碍了单个轨道的签名。