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We have grown M-plane GaN films with self-assembled C-plane GaN nanopillars on a γ-LiAlO2 substrate by plasma-assisted molecular-beam epitaxy. The diameters of the basal plane of the nanopillars are about 200 to 900 nm and the height is up to 600 nm. The formation of self-assembled c-plane GaN nanopillars is through nucleation on hexagonal anionic bases of γ-LiAlO2. Dislocation defects were observed and analyzed by transmission electron microscopy. From the experimental results, we developed a mechanism underlying the simultaneous growth of three-dimensional c-plane nanopillars and two-dimensional M-plane films on a γ-LiAlO2 substrate.

For the no-common-atom superlattices, the new phenomenon of zero-field spin splitting is predicted by the modified bond orbital model. Apart from the (001)- and (111)-oriented superlattices, this spin splitting appears along the growth directions of superlattices. Moreover, it originates from the existence of heterobonds inside the interfacial unit cells. This phenomenon due to the microscopic symmetry reduction is similar to the concept of the Dresselhaus effect and thus termed as the Dresselhaus-like spin splitting.

The interface perturbations at the atomic scale are neglected in the bond orbital model (BOM) due to the unit-cell-scale orbitals. This makes the breakdown of the higher symmetry Hamiltonian of BOM used for calculating the microscopic interface phenomena. To improve this problem, we introduce the intracell effects into the BOM by expanding the BOM basis in terms of the tetrahedral (anti)bonding orbitals and using the potential operator instead of the scalar potential for the extraction of the microscopic information. The modified BOM method provides the direct insight into the microscopic symmetry of the crystal chemical bonds in the vicinity of the heterostructure interfaces. It indicates more physical meanings and easier manipulations than the other methods in the mathematical calculations to discuss the symmetry breaking phenomena. The InAs–GaSb superlattice as an example can support the proposed model well.