从相变到非晶化：Yb注入β-Ga2O3中的损伤积累
From phase transformation to amorphization: damage accumulation in Yb-implanted $β-Ga_2O_3$
AI总结：
本研究通过多技术分析Yb注入β-Ga2O3的损伤演化，揭示其相变、缺陷积累及非晶化过程，发现氧化镓辐射耐受性受离子相互作用影响，挑战其高稳定性认知。
AI中文摘要：
本研究对不同取向的β-Ga2O3单晶在Yb离子注入下的辐射响应与结构演化进行了全面分析，注入注量范围为5×10^12至1×10^16 cm^-2（对应0.04至74 dpa）。研究采用多技术方法（RBS/c、PAS、HRTEM和HRXRD）探究损伤积累机制，结果揭示了缺陷演化的多阶段过程：在约0.4 dpa的临界阈值处，晶格应变积累触发单斜晶系β-Ga2O3向缺陷尖晶石结构γ-Ga2O3的相变，且该新相的形成伴随应变弛豫；随辐照进一步进行，γ-Ga2O3晶体结构内产生缺陷，此阶段相关的原子重组表现为损伤积累曲线出现明显下降，以及注入层亚表面区域出现堆垛层错。与此前认为该相具有高辐射稳定性的报道不同，本研究明确证实，持续的缺陷积累会导致 displaced atoms（移位原子）和空位型缺陷显著增加，且其类型与密度具有强烈的深度依赖性；最终在约7 dpa的辐照水平下，表面层发生非晶化，随辐照进一步进行，非晶层扩展，逐渐取代瞬态γ-Ga2O3相。这些发现表明，氧化镓的辐射耐受性对离子特异性相互作用和应变诱导不稳定性高度敏感，从而对该材料在高通量离子辐照下的固有稳健性提出了挑战。
英文摘要：
This study provides a comprehensive analysis of the radiation response and structural evolution of differently oriented$β-Ga_2O_3$ single crystals subjected to Yb ion implantation over a wide fluence range from $5 \times 10^{12}$ to $1 \times 10^{16}$~cm$^{-2}$ ($0.04$--$74$~dpa). A multi-technique approach (RBS/c, PAS, HRTEM, and HRXRD) was employed to investigate the mechanisms of damage accumulation. The results reveal a multi-stage process of defect evolution. At a critical threshold of around $0.4$~dpa, the accumulation of lattice strain triggers a phase transformation from monoclinic $β$-Ga$_{2}$O$_{3}$ to a defective spinel structure of $γ$-Ga$_{2}$O$_{3}$. Notably, the formation of this new phase is accompanied by strain relaxation. With further irradiation, defects develop within the crystal structure of $γ$-Ga$_{2}$O$_{3}$. The associated atomic reorganization at this stage is reflected by a distinct dip in the damage accumulation curve and the appearance of stacking faults in the subsurface region of the implanted layer. In contrast to previous reports suggesting high radiation stability of this phase, the present study clearly demonstrates that continuous defect accumulation results in a significant increase in both displaced atoms and vacancy-type defects, with a strong depth dependence in their type and density. Ultimately, at an irradiation level of approximately $7$~dpa, the surface layer amorphizes. With further irradiation, the amorphous layer expands, gradually replacing the transient $γ$-Ga$_{2}$O$_{3}$ phase. These findings reveal that the radiation tolerance of gallium oxide is highly sensitive to ion-specific interactions and strain-induced instabilities, thereby challenging the previously assumed robustness of this material under high-fluence ion irradiation.
