Fig. 1

Inclined side view of Al_xGa_1-xN/GaN heterojunctions with (a) x = 0.1250, (b) x = 0.1875, (c) x = 0.2500 and (d) x = 0.3125. Red dashed line: interface between Al_xGa_1-xN and GaN, N atoms (blue), Ga atoms (green), Al atoms (pink), and H atoms (white).