Aluminium oxide (AlO_x) tunnel junctions are important components in a range of nanoelectric devices including superconducting qubits where they can be used as Josephson junctions. While many improvements in the reproducibility and reliability of qubits have been made possible through new circuit designs, there are still knowledge gaps in the relevant materials science. A better understanding of how fabrication conditions affect the density, uniformity, and elemental composition of the oxide barrier may lead to the development of lower noise and more reliable nanoelectronics and quantum computers. In this paper, we use molecular dynamics to develop models of Al–AlO_x–Al junctions by iteratively growing the structures with sequential calculations. With this approach, we can see how the surface oxide grows and changes during the oxidation simulation. Dynamic processes such as the evolution of a charge gradient across the oxide, the formation of holes in the oxide layer, and changes between amorphous and semi-crystalline phases are observed. Our results are widely in agreement with previous work including reported oxide densities, self-limiting of the oxidation, and increased crystallinity as the simulation temperature is raised. The encapsulation of the oxide with metal evaporation is also studied atom by atom. Low density regions at the metal–oxide interfaces are a common feature in the final junction structures which persists for different oxidation parameters, empirical potentials, and crystal orientations of the aluminium substrate.

氧化铝（AlO _x）隧道结是许多纳米电器件（包括超导量子位）中的重要组件，在这些超导电量子位中，它们可用作约瑟夫森结。尽管通过新的电路设计使qubit的可复制性和可靠性有了许多改进，但相关材料科学仍存在知识空白。对制造条件如何影响氧化物阻挡层的密度，均匀性和元素组成的更好理解可能会导致噪声更低以及更可靠的纳米电子学和量子计算机的发展。在本文中，我们使用分子动力学来开发Al–AlO _x的模型–通过顺序计算迭代地增长结构来实现Al结。通过这种方法，我们可以看到在氧化模拟过程中表面氧化物如何生长和变化。观察到动态过程，例如整个氧化物上电荷梯度的演变，氧化物层中空穴的形成以及非晶相和半晶相之间的变化。我们的结果与以前的工作广泛一致，包括报告的氧化物密度，氧化的自限性以及随着模拟温度的升高结晶度的增加。还逐个原子地研究了通过金属蒸发对氧化物的封装。金属氧化物界面处的低密度区域是最终结结构的共同特征，对于不同的氧化参数，经验电势，