Gallium hydride vapor phase epitaxy of GaN nanowires

Straight GaN nanowires (NWs) with diameters of 50 nm, lengths up to 10 μm and a hexagonal wurtzite crystal structure have been grown at 900°C on 0.5 nm Au/Si(001) via the reaction of Ga with NH(3 )and N(2):H(2), where the H(2 )content was varied between 10 and 100%. The growth of high-quality GaN NWs depends critically on the thickness of Au and Ga vapor pressure while no deposition occurs on plain Si(001). Increasing the H(2 )content leads to an increase in the growth rate, a reduction in the areal density of the GaN NWs and a suppression of the underlying amorphous (α)-like GaN layer which occurs without H(2). The increase in growth rate with H(2 )content is a direct consequence of the reaction of Ga with H(2 )which leads to the formation of Ga hydride that reacts efficiently with NH(3 )at the top of the GaN NWs. Moreover, the reduction in the areal density of the GaN NWs and suppression of the α-like GaN layer is attributed to the reaction of H(2 )with Ga in the immediate vicinity of the Au NPs. Finally, the incorporation of H(2 )leads to a significant improvement in the near band edge photoluminescence through a suppression of the non-radiative recombination via surface states which become passivated not only via H(2), but also via a reduction of O(2)-related defects.