Effect of MgO buffer layer thickness on the electrical properties of MgZnO thin film transistors fabricated by plasma assisted molecular beam epitaxy

We report the fabrication and electrical characteristics of thin film transistors based on MgZnO thin films with different thicknesses of MgO buffer layer. The MgZnO thin films with MgO buffer layers were grown on SiO2/p-Si substrates by plasma assisted molecular beam epitaxy. The effects of the buffer layer thickness on the structural properties of MgZnO films are investigated by X-ray diffraction, and the results show that the crystal quality of the MgZnO film is enhanced with 4 nm MgO buffer layer. The MgZnO TFT with 4 nm MgO buffer layer exhibits an n-type enhancement mode characteristics with a field effect mobility of 1.85 cm2/V s, a threshold voltage of 27.6 V and an on/off ratio of above 106.

► MgZnO films with different thicknesses of MgO buffer layer were grown by MBE. ► MgZnO TFTs with different thicknesses of MgO buffer layer were fabricated. ► The crystal quality of MgZnO films was enhanced with 4 nm MgO buffer layer. ► MgZnO TFT with 4 nm MgO buffer layer showed the best performance.