New form of ordering in AlGaN

In contrast to the GaN/InN system where there is a lattice misfit about 10%, one would expect the growth of AlGaN to be more stable. In this work, we have found that the growth of AlGaN may be more complicated. Not only can the wurtzite lattice be decreased to simple hexagonal by AlN/GaN ordering along the c-axis, but the growth can lead to other types of stacking. Even in the low Al composition range, 10–15%, we have found that a number of processes can operate an ordering into AlN/GaN into two simple hexagonal sublattices, and for the first time, a new type of chemical ordering where Ga and Al atoms are in a 3:1 ratio.