Figure 1

Formation enthalpies of Mg _Ga /Mg _Al and normalized C _Mg cprofile of AlGaN films. (a) In the bulk and (b) on the surface of Al _x Ga_{1 - x} N as a function of Al content under N-rich condition. (c) Normalized C_Mg of Al _x Ga_{1 - x} N (x = 0.33, 0.54) epilayers from the surface to bulk. The inset in (a) shows the calculated Al _x Ga_{1 - x} N lattice constants a and c as a function of Al content. The inset in (c) illustrates the source supply sequence of the conventional method.