Electric field-induced redistribution of free carriers at isotype (In,Ga)P/GaAs interfaces

Metal–semiconductor contacts are applied to study depth-resolved electrical characteristics of Si- and Zn-doped GaAs/(In,Ga)P/GaAs heterojunctions by capacitance–voltage measurements. The measured depth profiles of the carrier concentration are compared with calculations based on solutions of the Poisson equation. Different growth conditions are chosen in order to produce heterointerfaces with (In,Ga)P layers of various degrees of order. It is shown that (In,Ga)P ordering induces piezoelectric polarization charges at interfaces with GaAs, the density of which increases with higher degree of order. The related electric field results in a redistribution of free carriers. For weakly ordered (In,Ga)P, the interfaces are found to be of type I.