通过ScN薄膜离子注入诱导损伤积累导致金属-绝缘体转变
Damage accumulation induced metal-insulator transition through ion implantation of ScN thin films
AI总结：
通过离子注入诱导ScN薄膜损伤积累，揭示了低剂量和高剂量下不同缺陷生成机制，以及缺陷景观对金属-绝缘体转变和局域化强度的影响。
摘要：
离子注入是一种通过受控掺杂和缺陷工程来调节材料电性能的强大方法，应用于热电材料和微电子器件。钪氮化物（ScN）对辐射诱导的无序特别敏感，其输运特性跨越多个数量级，并涉及多种导电机制。在本研究中，我们研究了在初始缺陷状态下经历累积辐射损伤的 epitaxial ScN 薄膜的输运特性演变。一种现象学的损伤积累模型成功结合了温度依赖的电阻率和霍尔效应测量，以阐明缺陷积累对输运特性的影响，并提供了关于辐射诱导缺陷本质和积累的物理基础、定量见解。它揭示了两种不同的电活性缺陷生成区域。在低剂量下，直接冲击损伤产生稳定且孤立的受体型复合缺陷（VSc-X），其中VSc是钪空位，X表示残留杂质，导致电阻率逐渐增加。在高剂量下，缺陷积累通过多击过程主导，产生点缺陷积累和载流子局域化，导致跃迁主导的输运。这种局域化区域在热力学上不稳定，经低温退火后会恢复。我们进一步证明，残留的缺陷景观强烈影响金属-绝缘体转变的临界剂量和局域化强度：在Al2O3上生长的薄膜比在MgO上生长的薄膜更早发生转变且局域化更弱。这些结果突显了离子注入作为在ScN中工程由无序诱导局域化的有效途径，初始薄膜质量起决定性作用。
英文摘要：
Ion implantation is a powerful approach for tuning the electrical properties of materials through controlled doping and defect engineering, with applications in thermoelectrics and microelectronics. Scandium nitride (ScN) is particularly sensitive to irradiation-induced disorder, with transport properties spanning several orders of magnitude and multiple conduction mechanisms involved. In this study, we investigate the evolution of electrical transport in epitaxial ScN thin films undergoing accumulated irradiation damage at an initial defect state. A phenomenological damage-accumulation model was successfully combined with temperature dependent resistivity and Hall effect measurements to elucidate the impact of defect buildup on electrical transport and to provide physically grounded, quantitative insight into the nature and accumulation of irradiation-induced defects. It reveals two distinct defects-generation regimes of electrically active defects. At low doses, direct-impact damage produces stable and isolated acceptor-type complex defects, (VSc-X) with VSc a scandium vacancy and X denoting residual impurities, leading to a gradual increase in resistivity. At higher doses, defect accumulation dominates through a multi-hit process, giving rise to point-defect buildup and carrier localization, resulting in hopping-dominated transport. This localized regime is thermally unstable and recovers upon low-temperature annealing. We further demonstrate that the residual defect landscape strongly influences both the critical dose for the metal-insulator transition and the localization strength: films grown on Al2O3 exhibit an earlier transition and weaker localization than those grown on MgO. These results highlight ion implantation as an effective route for engineering disorder-induced localization in ScN, with the initial film quality playing a decisive role.
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