The spin-splitting energies of the conduction band for ideal wurtzite materials are calculated within the nearest-neighbor tight-binding method. It is found that ideal wurtzite bulk inversion asymmetry yields not only a spin-degenerate line ͑along the k z axis͒ but also a minimum-spin-splitting surface, which can be regarded as a spin-degenerate surface in the form of bk z 2 − k ʈ 2 =0 ͑b Ϸ 4͒ near the ⌫ point. This phenomenon is referred to as the Dresselhaus effect ͑defined as the cubic-ink term͒ in bulk wurtzite materials because it generates a term ␥ wz ͑bk z 2 − k ʈ 2 ͒͑ x k y − y k x ͒ in the two-band k • p Hamiltonian.

Spin-splitting energies of wurtzite AlN and InN are calculated using the linear combination of atomic orbital method, and the data are analyzed utilizing the two-band k • p model. It is found that in the k • p scheme, a spin-degenerate surface exists in the wurtzite Brillouin zone. Consequently, the D'yakonov-Perel' spin relaxation mechanism can be effectively suppressed for all spin components in the ͓001͔-grown wurtzite quantum wells ͑QWs͒ at a resonant condition through application of appropriate strain or a suitable gate bias. Therefore, wurtzite QWs ͑e.g., InGaN/AlGaN and GaN/ AlGaN͒ are potential structures for spintronic devices such as the resonant spin lifetime transistor.

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The 2×2 conduction band, 4×4 hole band, and 2×2 spin-orbit split-off band matrices of zincblende semiconductors are obtained by using a block diagonal technique. Importantly, the block diagonal matrices incorporate not only the interband coupling effect but also the bulk inversion asymmetry effect. Analytical expressions for the conduction band spin-splitting energies of GaAs zincblende bulk and quantum wells grown on [001]-, [111]-, and [110]-oriented substrates are formulated by solving the block diagonal matrices. The results show that odd-in-k terms exist in both the bulk and the quantum well expressions due to the bulk inversion asymmetry effect. The presence of these terms is shown to induce the spin-splitting phenomenon.

The influence of bulk inversion asymmetry (tetrahedral) on the optical transitions in zinc blende quantum wells is analyzed using an enhanced k∙p optical calculation framework which takes intracell interactions into account. It is shown that inversion asymmetry results in a marked variation of the optical transition strength. Significantly, this effect cannot be revealed by the conventional k∙p optical transition formalism, which considers intercell interactions only.

An 8 ϫ 8 band edge potential matrix of the ͓hkil͔-oriented wurtzite Hamiltonian is developed and applied to explore optical anisotropy in ͓hkil͔-oriented wurtzite semiconductor quantum wells. The wave-vector-dependent optical matrix elements are expressed entirely in terms of Hamiltonian matrix elements, thus avoiding the requirement to introduce any additional optical parameters. To accommodate the noncubic symmetry of the wurtzite lattice, spinor rotation is taken into account when performing the calculations for different crystal orientations. The optical matrix elements are formulated and calculated for both the real finite-barrier-height case and the approximate infinite-barrier-height case. It is found that giant anisotropy of the optical matrix elements appears in the ͓1010͔and ͓1012͔-oriented well planes.

Investigation of optical anisotropy spectra in the R-plane (i. e., the [1012]-oriented layer plane) of GaN/Al 0.2 Ga 0.8 N quantum wells with different widths is studied. The optical matrix elements in the wurtzite quantum wells are calculated using the k•p finite difference scheme. The calculations show that the valence band mixing effect produces giant in-plane optical anisotropy in [1012]-oriented GaN/Al 0.2 Ga 0.8 N quantum wells with a narrow width. The nature of the in-plane optical anisotropy is found to be dependent on the well width. Specifically, it is found that the anisotropy changes from x-polarization to y-polarization as the well width increases.