Crystallization of HfO 2 in InAs/HfO 2 core–shell nanowires

We report the impact of deposition parameters on the structure of HfO 2 covering InAs nanowires (NWs) being potential candidates for future field-effect transistors (FETs). Molecular beam epitaxial-grown Au-free InAs NWs were covered with HfO 2 deposited by atomic-layer deposition. The impact of the film thickness as well as the deposition temperature on the occurrence and amount of crystalline HfO 2 regions was investigated by high-resolution transmission electron microscopy (TEM) and x-ray diffraction. Compared to the deposition on planar Si substrates, the formation probability of crystalline HfO 2 on InAs NWs is significantly enhanced. Here, even 3 nm thick films deposited at 250 °C are partly crystalline. Similarly, a low deposition temperature of 125 °C does not result in completely amorphous 10 nm thick HfO 2 films, they contain monoclinic as well as orthorhombic HfO 2 nanocrystals. Combining HfO 2 and A...

T Rieger, T Jörres, J Vogel, A Biermanns, U Pietsch, D Grützmacher and M I Lepsa

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