The lack of a lattice-matched substrate for epitaxial growth of GaN films has stimulated an intense search for suitable materials. 2 was an obviously promising possibility for GaN epitaxy, because its crystal structure is just a wurtzite superstructure and could be grown by the Czochralski technique. Figure 1 shows the crystal structure of tetragonal -LiAlO 2 . The structure is chiral.
Alternate slabs are mirror twins.
The lattice match to GaN for this orientation relationship is also very good. In this paper we examine the orientation relationships and microstructure for GaN and AlN films grown directly on -LiAlO 2 . We suggest that this tilt is driven by interface energies rather than strain. A normal amount of oxygen outgassing was observed during this stage, and no Li was observed by quadrupole mass spectroscopy. It was noted that exposure to the 7.5 keV electron beam resulted in a darkening of a -LiAlO 2 substrate.