Vibrational properties of atomically thin semiconductors on ultra-flat metals
Abstract
Transition metal Dichalcogenides, or TMDs are a class of semiconducting two dimensional materials with numerous possible applications in various fields such as biotechnology and optoelectronics. Molybendum disulfide or MoS2 is the most widely used and studied TMD due to its ease of attainment and exfoliation. In this work, the effects of different substrates on the vibrational properties of MoS2 were studied via Raman Spectroscopy. The substrates that were studied were Silicon dioxide (SiO2), hexagonal boron nitride (h-BN), and atomically flat gold (Au). These measurements were carried out for temperatures ranging from 300k to 1.5k, for external magnetic field strengths ranging from 0 to 9 (and -9) Tesla, and for mono, bi, tri, and quadlayer MoS2 samples. For each of the variables, shift in peak position, shifts in peak width, and changes in peak intensity were recorded and plotted. For the data on peak positions vs temperature, the data was fitted using a least squares linear fit and the rates of change of Raman peak energy with respect to temperature (alpha values) were found. This research found that peaks were generally (with one exception) redshifted on Au compared to SiO2. As temperature went up, peaks redshifted as well. The B field dependence of the peaks was found to be negligible. The alpha values for the E and A1 peaks on bilayer MoS2/Au were found to be -0.0135 +/- 0.0035 cm^-1/K and 0.0143 +/- 0.0052 cm^-1/K, respectively. The alpha values for the E and A1 peaks on trilayer MoS2/Au were found to be -0.0086 +/- 0.0027 cm^-1/K and -0.0115 +/- 0.0033 cm^-1/K respectively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 20, 2022
- Accession Number
- AD1223856
Entities
People
- Daniel C. Touzeau
Organizations
- San Francisco State University