Selectively dopedn-AlxGa1−xAs/GaAs heterostructures with high-mobility two-dimensional electron gas for field effect transistors

In selectively dopedn-Al_xGa_1–xAs/GaAs heterostructures with high-mobility two-dimensional electron gas (2 DEG) at the heterointerface a second conductive channel exists, if the Al_xGa_1–xAs layer is not totally depleted from free carries. The occurrence of parallel conductance has a deleterious effect on the performance of high-electron mobility transistors (HEMTs) fabricated from this material. Although in principle computable, parallel conductance depends on a large number of design parameters to be chosen for the heterostructure, which are additionally affected by the presence of deep electron traps inn-Al_xGa_1–xAs of composition 0.25n-Al_xGa_1–xAs/GaAs heterostructures is shown.