IMPROVED FITS OF THE EFFECTIVE MASSES AT GAMMA IN THE SPIN-ORBIT, 2ND-NEAREST-NEIGHBOR SP(3)S-ASTERISK MODEL - RESULTS FROM ANALYTIC EXPRESSIONS

We derive and study exact analytic expressions for the effective masse s of the conduction-and all three hole-bands at Gamma in the spin-orbi t, second-nearest-neighbor sp(3)s model. Using these expressions we d etermine parameters for six common III-V materials (GaAs, AlAs, GaSb, AlSb, InAs, and InP), tailored for [001]-oriented heterostructure calc ulations. Beyond their use in fitting band structures, the effective-m ass formulas show that the second-nearest-neighbor sp(3)s model is no t without Limitations. We show that there is an upper bound on the rep roducible electron-light-hole effective-mass mismatch, so that even th is model may not be sufficient for certain materials.