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|標題:||Valence band properties of relaxed Ge1-xCx alloys||作者:||Lin, C.Y.
|關鍵字:||GeC alloys;hole effective mass;linear combination of atomic orbitals;valence band;non-parabolicity;growth;performance;diamond||Project:||Materials Chemistry and Physics||期刊/報告no：:||Materials Chemistry and Physics, Volume 52, Issue 1, Page(s) 31-35.||摘要:||
We report hole effective mass calculations of Ge1-xCx alloys. A 16 x 16 Hamiltonian matrix constructed from the linear combination of atomic orbitals with spin-orbit interaction terms is used for the calculations. The properties of alloys are calculated under the virtual crystal approximation. The 1 meV constant energy surface below the valence band edge is used to determine the nominal hole effective masses. Calculations are carried out by taking the diamond split-off energy Delta Es-o(C) as 0 and 6 meV, respectively. In both cases, the light hole band results of Ge1-xCx alloys agree to within less than 1%. The effective masses of light hole increase monotonically from 0.078 m(0) (for pure Ge) to 0.19 m(0) (for pure C) while the non-parabolicity drops rather monotonically. The heavy hole effective masses of the alloys show a highly non-linear dependence on the carbon content (x). The results in both cases are indistinguishable from x=0.0 to about x=0.9; it decreases slightly from x=0.0 to x=0.5 and increases slowly from x=0.5 to x=0.9. The values increase for x > 0.9. With Delta Es-o(C)=0 meV, there is an abrupt increase by a factor of two from x=0.97 to x=1.0 to a value of 0.89 m(0). For Delta Es-o(C)=6 meV, a similar trend is found with a lower value of 0.45 nz, at x=1.0. The non-parabolicity of the heavy hole masses increases monotonically from x=0.0 to x=0.99, and nearly disappears for pure diamond for Delta Es-o(C)=0 meV, while a monotonic increase of non-parabolicity is found for Delta Es-o(C)=6 meV from pure Ge to pure C. The interaction between the split-off hole band and the heavy hole band is proposed for the anomalous behavior of the heavy hole effective masses of GeC alloys. (C) 1998 Elsevier Science S.A.
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