Discipline: Chemistry and Chemical Sciences
Subcategory: Materials Science
Victoria Jones - Penn State University
Co-Author(s): Tanushree Choudhury and Joan Redwing, Penn State University
A direct bandgap of 1.8 eV, mechanical strength and flexibility, and notable photoresponsivity makes MoS2 a 2D semiconductor that could be utilized in flexible electronics, photodetectors, and solar cells. These properties can be harnessed more efficiently if site-specific growth could be achieved. It is expected that seeding could provide central nucleation points, thereby facilitating growth and control on the orientation of the nuclei on the substrate. In addition to oriented growth, controlling the doping of MoS2 is critical for efficient device performance. As MoS2 is intrinsically n-type, p-type doping is crucial. Based on theoretical studies niobium was selected as the p-type dopant and Nb2O5 as the precursor.
MoS2 was deposited using MoO3 source, at a temperature range of 650-750°C with the sulfur boat placed upstream at 120°C. The deposition was done at atmospheric pressure with a flow rate of 200 sccm, and the deposition profile at different substrate separation was ascertained. For the oriented growth Au droplets on sapphire substrates were used. 5-10 nm thick Au films deposited on sapphire substrate were annealed at 1000°C to form Au droplets of various sizes, which were then used for the powder vaporization of MoS2. For doping, deposition of NbS2 was separately attempted for a temperature range of 700-950°C. Samples were analyzed via Raman spectroscopy, optical microscopy, XPS and SEM.
Funder Acknowledgement(s): NSF; Penn State University
Faculty Advisor: Joan Redwing, firstname.lastname@example.org
Role: I was responsible for the powder vaporization synthesis of MoS2, annealing of 5-10 nm thick Au films deposited on sapphire substrate, deposition of NbS2 was separately attempted for a temperature range of 700-950°C, and sample analysis via Raman spectroscopy, optical microscopy, XPS and SEM.