Enhancement of Schottky barrier height in heterodimensional metal-semiconductor contacts

We report on the measurements of the heterodimensional Schottky barrier height in two-dimensional metal-semiconductor field effect transistors (2D MESFETs). Our experimental data indicate approximately 0.1 eV greater barrier height compared to conventional metal-semiconductor contacts of the same materials. The enhancement is explained in terms of two effects—quantization of energy levels of the carriers in the quantum well and broadening of the corresponding wave functions. The increased barrier height leads to a substantial reduction of the gate leakage current in 2D MESFETs.