Determination of $g$-factor in InAs two-dimensional electron system by capacitance spectroscopy

We determine the effective $g$-factor ($|g^\ast|$) of a two-dimensional electron gas (2DEG) using a new method based on capacitance spectroscopy. The capacitance-voltage profile of a 2DEG in an InAs/AlGaSb quantum well measured in an in-plane magnetic field shows a double-step feature that indicates the Zeeman splitting of the subband edge. The method allows for simultaneous and independent determination of $|g^\ast|$ and effective mass $m^\ast$. Data suggest that the biaxial tensile strain in the InAs layer has considerable impacts on both $m^\ast$ and $g^\ast$. Our method provides a means to determine $|g^\ast|$ that is complementary to the commonly used coincidence technique.