Low Temperature Growth of Boron

High growth temperatures (>1100 °C), low production yield, and impurities have prevented research progress and applications of boron nitride nanotubes (BNNTs) in the past 10 years. Here, we show that BNNTs can be grown on substrates at 600 °C. These BNNTs are constructed of high-order tubular structures and can be used without purification. Tunneling spectroscopy indicates that their band gap ranges from 4.4 to 4.9 eV. Boron nitride nanotubes (BNNTs) were first predicted in 19941,2 and experimentally realized in the following year.3 They are structurally similar to carbon nanotubes (CNTs) and exhibit extraordinary mechanical properties.4-6 Despite these similarities, BNNTs are different from CNTs in other aspects. They possess uniform electronic properties that are insensitive to their diameters and chiralities.1,2 Theoretically, their band gaps (5 eV) are tunable and can even be eliminated by transverse electric fields through the giant dc Stark effect.7-9 In addition, BNNTs demonstrate high oxida