Theoretical studies on the two-dimensional electron-gas properties of MgZnO/MgO/ZnO heterostructures

The polarization effects on the two-dimensional electron-gas (2DEG) of the ZnO/MgO/MgZnO heterostructure were theoretically investigated. The carrier confinement in the MgZnO/MgO/ZnO high-electron-mobility transistor (HEMT) structure is shown to be superior to that in the conventional MgZnO/ZnO HEMT structure. The electron density is shown to be very sensitive to the layer thickness and to become a maximum at a layer thickness of 2 nm. Also, the MgZnO/MgO/ZnO HEMT structure shows a larger saturation drain current than the conventional MgZnO/ZnO HEMT structure does. This is mainly due to the increased channel electron density induced by the enhanced polarization charge with the inclusion of the MgO layer.