Electronic structures and total energies obtained by ab initio quantum theory were used to calculate the spectroscopic and structural properties of semiconductors under pressure. Some III-V nitrides were considered as examples. The pressure dependence of various defect levels were considered, as well as the variation in defect formation energies with applied pressure. The results were compared with similar work on defects in GaAs. Dilute GaAs1-xNx compounds were examined by means of calculations using large super-cells. The introduction of small amounts of N strongly modified the conduction bands; the Γ, L and X states mixed and formed new low-energy states. The identification of the so-called E+ state as being a1(L1c) was confirmed. The lowest conduction band exhibited a strong non-parabolicity. Pressure strongly affected the electronic properties of GaAs1-xNx, and influenced the effective electron masses and their dependence upon x. The results obtained for the dilute N-alloys differed significantly from recent data on Ga1-xBxAs.

Theoretical Studies of Semiconductors, with and without Defects, under Pressure. N.E.Christensen, I.Gorczyca, A.Svane, N.G.Szwacki, P.Boguslawski: Physica Status Solidi B, 2003, 235[2], 374-83