Diffusion mechanism and the thermal stability of fluorine ions in GaN after ion implantation
Diffusion mechanism and the thermal stability of fluorine ions in GaN after ion implantation
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DOI：
10.1063/1.3106561
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发表时间：
2009-04
影响因子：
3.2
通讯作者：
Mingxiang Wang;Li Yuan;K. J. Chen;F. Xu;B. Shen
中科院分区：
文献类型：
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作者：
Mingxiang Wang;Li Yuan;K. J. Chen;F. Xu;B. Shen
利用飞行时间二次离子质谱研究了氟离子在GaN中的扩散机制。代替通过氟等离子体处理将氟离子结合到靠近样品表面，利用具有180 keV的能量的氟离子注入将氟离子深深地注入到GaN块体中，防止表面效应影响数据分析。研究发现，氟离子在GaN中的扩散是一个动态过程，其特征是先向外扩散，然后向内扩散，最后稳定化。提出了一个空位辅助扩散模型来解释实验观察，这也是一致的分子动力学模拟的结果。氟离子倾向于占据离子注入引起的Ga空位并扩散到空位富集区。通过动态热退火过程可以显著减少连续空位链的数量。结果表明，GaN晶体中氟离子具有很强的局域约束和稳定性，表明氟离子具有优异的热稳定性，可用于器件应用。
The diffusion mechanisms of fluorine ions in GaN are investigated by means of time-of-flight secondary ion mass spectrometry. Instead of incorporating fluorine ions close to the sample surface by fluorine plasma treatment, fluorine ion implantation with an energy of 180 keV is utilized to implant fluorine ions deep into the GaN bulk, preventing the surface effects from affecting the data analysis. It is found that the diffusion of fluorine ions in GaN is a dynamic process featuring an initial out-diffusion followed by in- diffusion and the final stabilization. A vacancy-assisted diffusion model is proposed to account for the experimental observations, which is also consistent with results on molecular dynamic simulation. Fluorine ions tend to occupy Ga vacancies induced by ion implantation and diffuse to vacancy rich regions. The number of continuous vacancy chains can be significantly reduced by a dynamic thermal annealing process. As a result, strong local confinement and stabilization of fluorine ions can be obtained in GaN crystal, suggesting excellent thermal stability of fluorine ions for device applications.