Molybdenum disulfide (MoS 2 ) thin films were grown directly on SiO 2 covered wafers by atomic layer deposition (ALD) at the deposition temperatures ranging from 175 to 225 °C using molybdenum hexacarbonyl [Mo(CO) 6 ] and H 2 S plasma as the precursor and reactant, respectively. Self-limited film growth on the thermally-grown SiO 2 substrate was observed with both the precursor and reactant pulsing time. The growth rate was ∼0.05 nm/cycle and a short incubation cycle of around 13 was observed at a deposition temperature of 175 °C. The MoS 2 films formed nanocrystalline microstructure with a hexagonal crystal system (2H-MoS 2 ), which was confirmed by X-ray diffraction and transmission electron microscopy. Single crystal MoS 2 nanosheets, ∼20 nm in size, were fabricated by controlling the number of ALD cycles. The ALD-MoS 2 thin films exhibited good stoichiometry with negligible C impurities, approximately 0.1 at.% from Rutherford backscattering spectrometry (RBS). X-ray photoelectron spectroscopy confirmed the formation of chemical bonding from MoS 2 . The step coverage of ALD-MoS 2 was approximately 75% at a 100 nm sized trench. Overall, the ALD-MoS 2 process made uniform deposition possible on the wafer-scale (4 in. in diameter).
Bibliographical noteFunding Information:
This study ( 2015R1A2A2A04004945 ) was supported by the Mid-career Researcher Program through NRF grant funded by the MEST and also partially supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and NRF, Korea ( NRF-2014H1C1A1066809 ) and Human Resources Program in the Transportation Specialized Lighting Core Technology Development granted financial resource from the Ministry of Trade, Industry and Energy (No. N0001364 ).
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films