In-situ scanning transmission electron microscopy study of Al-amorphous SiO2 layer-SiC interface

Here, we present a comprehensive study on atomic-scale in-situ biasing/heating scanning transmission electron microscopy ((S)TEM) of Al-amorphous SiO2-SiC interface. The investigation includes electrical, chemical, and structural analysis of the interface at different temperatures (25-600 degrees C). The results show that at similar to 500 degrees C the electrical (three-orders of magnitude resistivity drop), chemical (dissolution of SiO2 amorphous layer), and microstructural features (e.g. formation of Al2O3, Si and Al4C3) of the interface start to change. According to the results, amorphous SiO2 dissolves in Al, leading to formation of alpha-Al2O3 and Si within the Al. In contrast, elemental interdiffusion (Al3+ reversible arrow Si4+) between Al and SiC occurs resulting in formation of Al4C3. From the results, we can infer that reaction mechanism between Al and crystalline SiC is different with that between Al and SiO2 amorphous phase. It is believed that structural similarities between SiC and Al4C3 play an important role in paving the way for elemental interdiffusion.