Hardness and Young's modulus of high-quality cubic boron nitride films grown by chemical vapor deposition

We report a method of making nanowires of bismuth (Bi) with diameters ranging from 30 to 200 nm and lengths up to several millimeters. The nanowires are extruded spontaneously at the rate of a few micrometers per second at room temperature from the surfaces of freshly grown composite thin films consisting of Bi and chrome–nitride. The high compressive stress in these composite thin films is the driving force responsible for the nanowire formation. This mechanism can also be used to create nanowires of other materials.

Epitaxial Al1−xInxN thin films with 0⩽x⩽1 have been grown by plasma source molecular beam epitaxy on sapphire (0001) substrates at a low temperature of 375 °C. Both reflection high-energy electron diffraction and x-ray diffraction measurements confirm the c-plane growth with the following epitaxial relations: nitride [0001] ∥ sapphire [0001] and nitride 〈011̄0〉 ∥ sapphire 〈21̄1̄0〉. However, the degree of crystalline mosaicity and the compositional fluctuation increase with increasing x. The observed direct energy band gap, determined using optical transmission and reflection measurements show relatively less bowing compared to some earlier studies. Electrical resistivity and Hall effect measurements show n-type electrical conductivity in these alloys with carrier concentrations n⩾1019 cm−3 for In-rich alloys and n⩽1010 cm−3 for Al-rich alloys.

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