Characterization of Molybdenum Oxide Thin Films Grown by Atomic Layer Deposition

Molybdenum oxide (MoO3) thin films have been deposited using plasma-enhanced atomic layer deposition with molybdenum hexacarbonyl (Mo(CO)(6)) and oxygen plasma. Self-limiting growth was verified at a deposition temperature of 162 degrees C and the growth rate was determined to be 0.76 angstrom/cycle. It was found that the as-deposited amorphous thin films crystallized into - or -MoO3 during annealing temperatures from 300 degrees C to 400 degrees C in air. In addition, the optical bandgap (E-g) of the amorphous MoO3 was estimated to be 4eV by transmittance spectral analysis. Moreover, metal-insulator-semiconductor capacitors based on p-type (100) silicon substrates were fabricated to investigate the electrical properties of MoO3. It was shown that the MoO3 thin films exhibit a good dielectric performance and that the dielectric constant of the amorphous MoO3 was determined to be about 17. Additionally, a low leakage current of 6.43x10(-7)A/cm(2) at 1V was detected and the equivalent oxide thickness was calculated to be 10.5nm. As a result, MoO3 thin films, as a new high- gate dielectrics system, might be a good candidate for metal-insulator-semiconductor field-effect transistors based on two-dimensional transition metal dichalcogenides, especially for metal oxide semiconductor field-effect transistors using molybdenum disulfide (MoS2) as channel material.