The growth mechanism of the CuO single-crystal nanowires (NWs) for future device applications has been demonstrated using the copper films deposited on CuO-buffered SiO2/Si substrates. The mechanism involves a two-step process: In the first step, hillocks of copper are formed to relieve the compressive stress existing on the copper films at high temperature for a long duration of time in air and then Cu2O phase is formed by the oxidation of the hillocks in air ambient. The second step involves a continuous supply of copper through the porous Cu2O seed and then the transformation of the Cu2O phase to CuO NW. The CuO NW was grown by a continuous supply of both copper from the copper films and oxygen from air. The indispensable requirements for CuO NW growth from the copper films are the presence of compressive stress in the copper films and the presence of the Cu2O seed phase on the copper films at a high temperature in air.

Phase-change InSbTe (IST) single crystalline nanowires were successfully synthesized at a low temperature of 250 degrees C by metalorganic chemical vapor deposition (MOCVD). The growth of IST nanowires by MOCVD, at very high working pressure, was governed by supersaturation. The growth mechanism of the IST nanowires by MOCVD is addressed in this paper. Under high working pressure, the InTe phase was preferentially formed on the TiAlN electrode, and the InTe protrusions were nucleated on the InTe films under high supersaturation. The Sb was continuously incorporated into the InTe protrusions, which was grown as an IST nanowire. Phase-change-induced memory switching was realized in IST nanowires with a threshold voltage of about 1.6 V. The ability to grow IST nanowires at low temperature by MOCVD should open opportunities for investigation of the nanoscale phase-transition phenomena.

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