Gating of Two-Dimensional Electron Systems in (In,Ga)As/(In,Al)As Heterostructures: The Role of Intrinsic (In,Al)As Deep Donor Defects

We present an analysis of gated (In, Ga)As/(In, Al)As heterostructures, a device platform to realize spin-orbitronic functionalities in semiconductors. The phenomenological model deduced from our magnetotransport experiments allows us to correlate the gate response of the two-dimensional electron systems with the design parameters of the heterostructure, in particular the indium concentration. We explain the occurrence of metastable electrostatic configurations showing reduced capacitive coupling and provide gate-operation strategies to reach classical field-effect control in such heterostructures. Our study highlights the role of the intrinsic (In, Al)As deep donor defects, as they govern the dynamics of the electrostatic response to gate-voltage variations through charge trapping and unintentional tunneling.