Thursday 23 January 2025
Researchers at the University of Poitiers and IMEC have been studying the effects of pre-treatment on Co-germanide Schottky contacts, a crucial component in future transistors. The team found that cleaning the germanium substrate before depositing cobalt can significantly impact the electrical properties of the device.
The researchers started by depositing a thin layer of cobalt onto germanium substrates that had been pre-treated at either 400°C or 700°C. They then performed a post-metal deposition annealing to form the Co-germanide films. The team used various techniques, including transmission electron microscopy (TEM), atomic force microscopy (AFM), and deep-level transient spectroscopy (DLTS) to analyze the samples.
The results showed that the pre-treatment temperature had a significant impact on the formation of the Co-germanide films. At 400°C, the native oxide was not fully removed, leading to the presence of contaminants in the film. In contrast, the 700°C pre-treatment removed the native oxide and allowed for the formation of a smoother film with fewer defects.
The team also found that the electrical properties of the device changed significantly depending on the pre-treatment temperature. The Schottky barrier height increased with increasing pre-treatment temperature, while the leakage current decreased. This suggests that the cleaning process can improve the overall performance of the device by reducing the number of defects and contaminants.
One surprising finding was the formation of a double layer structure in the Co-germanide film after post-metal deposition annealing at 700°C. The top layer was found to be a discontinuous monocrystal of Co5Ge7, while the underlayer consisted of grains of Co5Ge7 and CoGe2. This unique microstructure is thought to be the result of interdiffusion between the cobalt and germanium.
In contrast, the sample pre-treated at 400°C showed large isolated islands on its surface after post-metal deposition annealing. The mechanisms behind this formation are still unclear and require further investigation.
The researchers believe that their findings have important implications for the development of future transistors. By understanding how to optimize the cleaning process and improve the formation of Co-germanide films, they hope to create devices with better electrical properties and higher performance.
Overall, this study highlights the importance of pre-treatment in the fabrication of Co-germanide Schottky contacts.
Cite this article: “Pre-Treatment Effects on Co-Germanide Schottky Contacts”, The Science Archive, 2025.
Co-Germanide, Schottky Contacts, Pre-Treatment, Germanium, Cobalt, Transistor, Tem, Afm, Dlts, Microstructure.
