Variable density high mobility two-dimensional electron and hole gases in a gated GaAs/Al<i>x</i>Ga1−<i>x</i>As heterostructure

Abstract

We have fabricated undoped GaAs/AlxGa1−xAs heterojunctions in which an electric field produced by a top gate confines carriers to the interface, and where contact is made to carriers at the interface using a novel self-aligned contacting process. Densities for both electrons and holes ranging from n2D &amp;lt; 1010/cm2 to n2D ≳ 5 × 1011/cm2 are obtainable with mobilities comparable to those measured in high quality modulation-doped heterojunctions.