Various reconstructions on the (00•1) surface were studied by scanning tunnelling microscopy. On the basis of a comparison between scanning tunnelling microscopy observations and first-principles total-energy calculations, an adatom scheme was proposed for the basic 2 x 2 and 4 x 4 structures, among others. It was revealed that the 5 x 5 phase consisted of a linear chain of unevenly displaced Ga adatoms, along the [11•0] direction, due to lattice relaxation. The Ga-adatom scheme could explain all of these structures, and indeed, all other stable reconstructions on this surface; such as v7 x v7, 6 x 6, 5v3 x 2v13, 10 x 10 and 1 x 1. Some N-rich structures which were predicted theoretically were difficult to access kinetically.

Structures of GaN(00•1)-(2 x 2), -(4 x 4) and -(5 x 5) surface reconstructions Q.K.Xue, Q.Z.Xue, R.Z.Bakhtizin, Y.Hasegawa, I.S.T.Tsong, T.Sakurai, T.Ohno: Physical Review Letters, 1999, 82[15], 3074-7