Magneto-optical properties of theGaxIn1−xSesystem near the fundamental band gap

Abstract

We have studied the magneto-optical properties of the ${\mathrm{Ga}}_x{\mathrm{In}}_{1-x}\mathrm{Se}$ system in the indium-rich and gallium-rich regions near the fundamental band gap by wavelength-modulation spectroscopy at 10 K with the electric vector $\overrightarrow{\mathrm{E}}$ perpendicular to the $\overrightarrow{\mathrm{C}}$ axis of the crystal. For the first time, Landau levels have been observed in InSe from which we obtain the reduced effective mass perpendicular to $\overrightarrow{\mathrm{C}}$, ${\mu }_{\perp }=(0.090\mathrm{}\pm 0.010)m_0$. The $n=1, 2, \mathrm{and} 3$ exciton lines were observed as a function of the applied magnetic field, permitting us to evaluate the dependence of the effective Rydberg constant, the diamagnetic shift ${\epsilon }_{\perp }{\epsilon }_{\parallel }$, the exciton Bohr radius ${\epsilon }_{\parallel }$, the band gap, and ${\mu }_{\perp }$ on the compositional parameter $x$. Finally, we give evidence for the presence of the $\gamma$ and $\epsilon$ polytypes in the alloy system due to stacking faults.