Effect of surface treatments on ALD Al2O3/4H-SiC metal-oxide-semiconductor field-effect transistors

Silicon carbide (4H) based metal-oxide-semiconductor field-effect transistors provide capabilities in high power and high temperature inaccessible to silicon. However, the performance of thermally grown oxide-based devices remains limited by oxide/semiconductor interface defects. This research employs deposited dielectrics, Al2O3, rather than thermal oxidation. Investigation of various pre-deposition processes reveals different degrees of improvements in the electronic properties. An optimum structure employs the preparation of a nitrided surface via NO annealing, a process known to passivate surface defects, a hydrogen exposure, followed by Al2O3 deposition. Inversion layer field-effect mobilities as high as 52cm(2)/Vs are reported in the optimum structures. Capacitance-voltage measurements and field-effect mobility characteristics indicate a trapping limited conductivity in Al2O3/4H-SiC inversion channels similar to SiO2/4H-SiC. Leakage currents and interface breakdown are also reported for various Al2O3/4H-SiC MOS structures.

Automated summary

Silicon carbide (4H) based metal-oxide-semiconductor field-effect transistors offer capabilities in high power and high temperature that silicon cannot achieve. This research investigates the use of deposited Al2O3 dielectrics instead of thermal oxidation, resulting in improved electronic properties. The optimal structure involves preparation of a nitrided surface through NO annealing, hydrogen exposure, and Al2O3 deposition, leading to high inversion layer field-effect mobilities. Leakage currents and interface breakdown are also observed in various Al2O3/4H-SiC MOS structures.