Exciton spectra and energy band structure of CuAlS sub(2) crystals

Three exciton series are investigated in the reflectivity spectra of CuAlS sub(2) crystals at the temperature of 10 K. The n super(A)=1 ([Omega] sub(T)=3.543 eV, [Omega] sub(L)= 3.546 eV) and n super(A)=2 (3.565 eV) lines of the sub(4) (A-series) excitons are observed in the [double vertical bar]c polarization. In the [perpendicular]c polarization, the sub(5) excitons (n super(B)=1 at 3.668 eV and n super(B)=2 at 3.686 eV) of the B-series, and n super(C)=1 at 3.813 eV of the C-series are observed. The parameters of the excitons and the more exact values of the sub(7) - sub(6), sub(6) - sub(6), and sub(7) - sub(6) energy gaps are determined. The crystal field and spin-orbit splitting of the valence band is calculated. The electron [MathML equation] and hole ([MathML equation], [MathML equation], and [MathML equation]) effective masses have been estimated.