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Self‐consistent band structure and density of states calculations were performed for the pure alumina (corundum phase) and the aluminates α‐Al2–x Tx O3 where T is a transition metal and stands for Sc, Y, La and Ac with x = 0.5. In this study we have employed the full potential linear augmented plane wave (FPLAPW) with generalized gradient approximations (GGA) based on the density functional theory (DFT). The results show that the size of the band gap in these alloys decreases considerably and these reductions are related to the ionic radius of the substituted transition metal. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

An ensemble Monte Carlo simulation is used to compare bulk electron transport in wurtzite phase GaN , AlN and InN materials. Electronic states within the conduction band valleys at the Γ1, U, M, Γ3 and K are represented by non-parabolic ellipsoidal valleys centered on important symmetry points of the Brillouin zone. For all materials, it is found that electron velocity overshoot only occurs when the electric field is increased to a value above a certain critical field, unique to each material. This critical field is strongly dependent on the material parameters. Transient velocity overshoot has also been simulated, with the sudden application of fields up to ~5 × 107 Vm -1, appropriate to the gate-drain fields expected within an operational field effect transistor. The electron drift velocity relaxes to the saturation value of ~1.4 × 105 ms -1 within 4 ps, for all crystal structures. The steady state and transient velocity overshoot characteristics are in fair agreement with other recent calculations.