The role of Ga in the chemical vapor deposition growth of ternary AlxGa1−xN nanowires

The self-catalytic growth of AlxGa1−xN nanowires by chemical vapor deposition (CVD) with Ga, Al and NH3 as the source materials and sapphire (0 0 0 1) as the substrates was studied. The Al mass, the distance between Al and Ga, and the growth temperatures have an influence on the morphologies of the samples. Without Ga, no nanowires are obtained. The Al content x in AlxGa1−xN nanowires hardly changes with the starting mass of Al but slightly decreases with the increase in the growth temperature. We propose that it is Ga that acts as the catalyst during the self-catalytic growth of AlxGa1−xN nanowires since the higher desorption rate of Ga and the N rich condition result in the island growth of GaN on sapphire and the island growth mode favors the formation of nanowires with the incorporation of Al. The Al content x in AlxGa1−xN nanowires relies on the ratio of the saturation vapor pressure of Al to the sum of that of Ga and Al.