Formation and Metastability of Pair-Defects in Silicon

半导体中的缺陷表现出不同的电子态和不同的微观结构。在大多数情况下，缺陷的电荷状态决定了具有特定光学和电学性质的实际结构配置。位形空间中缺陷的能面有几个极小值，其中能量最低的称为稳定位形，其他所有亚稳态位形都是亚稳位形。亚稳和稳定配置之间的受控传输是在存储设备中存储信息的一种很有前途的方法。只有在少数情况下，这些缺陷的微观结构已经被识别出来，并确定了亚稳的来源。该项目旨在为亚稳态之间的转移机制提供新的见解，并确定这些缺陷结构，这些缺陷结构可能在未来用于在室温下工作的存储器件。由硅中过渡金属组成的对缺陷似乎是这些应用的有希望的候选者。到目前为止，大多数实验技术都未能深入了解不同构型的结构变化，这是因为缺陷缺乏敏感性或电荷中立性。我们将使用局域振动模式(LVM)光谱，它提供了对缺陷所有电荷状态的微观结构的直接洞察。因此，通过光致发光和红外吸收获得的实验结果与最新的LVMS计算结果相比较，是实现该项目目标所需的工具。

Defects in semiconductors exhibit different electronic states with different microscopic structures. In most cases, the charge state of the defect determines the actual structural configuration possessing specific optical and electrical properties. The energy surface of a defect in configurational space exhibits several minima the one with the lowest energy is called the stable configuration, whereas all others metastable configurations. A controlled transfer between metastable and stable configurations is a promising way to store information in a memory device. Only in a few cases the microscopic structure of these defects have been identified and the origin for the metastability was established. The proposed project aims to give new insight into the mechanisms of transfer between metastable states and to determine those defect structures, which could be of future use in memory devices operating at room temperature. Pair-defects consisting of transition metals in Si seem to be promising candidates for these applications. Most experimental techniques failed up to now to give an insight in the structural changes of the different configurations, due to the lack of sensitivity or charge neutrality of the defects. We will use local vibrational mode (LVM) spectroscopy, which provides direct insights into the microscopic structures for all charge states of the defects. Therefore, state-of-the-art calculations of LVMs in comparison with experimental results obtained by means of photoluminescence and infrared absorption are the tools to be employed to fulfill the goals of the project.