Calculated spin-orbit splitting of all diamond-like and zinc-blende semiconductors: Effects of p1/2 local orbitals and chemical trends

TL;DR

This paper systematically calculates the spin-orbit splitting in various diamond-like and zinc-blende semiconductors, revealing how chemical composition and bonding character influence SO effects with high accuracy.

Contribution

It provides a comprehensive first-principles analysis of spin-orbit splitting across all relevant semiconductors, including effects of p1/2 local orbitals and chemical trends.

Findings

SO splittings increase with anion atomic number

Covalent compounds show increasing SO splittings with cation atomic number

Ionic compounds show decreasing SO splittings with cation atomic number

Abstract

e have calculated the spin-orbit (SO) splitting $\Delta_{SO}=\epsilon (\Gamma_{8v}) - \epsilon (\Gamma_{7v})$ for all diamond-like group IV and zinc-blende group III-V, II-VI, and I-VII semiconductors using the full potential linearized augmented plane wave method within the local density approximation. The SO coupling is included using the second variation procedure, including the $p_{1/2}$ local orbitals. The calculated SO splittings are in very good agreement with available experimental data. The corrections due to the inclusion of the $p_{1/2}$ local orbital are negligible for lighter atoms, but can be as large as $\sim$250 meV for 6$p$ anions. We find that (i) the SO splittings increase monotonically when anion atomic number increases; (ii) the SO splittings increase with the cation atomic number when the compound is more covalent such as in most III-V compounds; (iii) the SO splittings decrease with the cation atomic number when the compound is more ionic, such as in II-VI and the III-nitride compounds; (iv) the common-anion rule, which states that the variation of $\Delta_{SO}$ is small for common-anion systems, is usually obeyed, especially for ionic systems, but can break down if the compounds contain second-row elements such as BSb;(v) for IB-VII compounds, the $\Delta_{SO}$ is small and in many cases negative and it does not follow the rules discussed above. These trends are explained in terms of atomic SO splitting, volume deformation-induced charge renormalization, and cation-anion $p$--$d$ couplings.