| Autor: |
Banswar D; Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India. bkrishna@mse.iitd.ac.in., Sahu RR; Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India., Srivatsava R; Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India. bkrishna@mse.iitd.ac.in., Hassan MS; Chemistry Department, Indian Institute of Technology, Delhi, India., Singh S; Chemistry Department, Indian Institute of Technology, Delhi, India., Sapra S; Chemistry Department, Indian Institute of Technology, Delhi, India., Das Gupta T; Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India., Goswami A; Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India. bkrishna@mse.iitd.ac.in., Balasubramanian K; Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, India. bkrishna@mse.iitd.ac.in. |
| Abstrakt: |
Plasmonics in metal nanoparticles can enhance their near field optical interaction with matter, promoting emission into selected optical modes. Here, using Ga nanoparticles with carefully tuned plasmonic resonance in proximity to MoSe 2 monolayers, we show selective photoluminescence enhancement from the B-exciton and its trion with no observable A-exciton emission. The nanoengineered substrate allows for the first direct experimental observation of the B-trion binding energy in semiconducting monolayers. Using temperature-dependent photoluminescence measurements, we show the following features of the MoSe 2 B-exciton family: (i) the trion binding energy has an observable temperature dependence with a decreasing trend towards low temperatures and (ii) the exciton-trion emission ratio varies non-monotonically with temperature with a steep increase in the trion emission at lower temperatures. Using detailed models, we identify the particle size required for selective excitation and describe the underlying physical processes. This opens newer avenues for selectively promoting excitonic species and tuning the effective particle lifetimes in monolayer semiconductors. These results demonstrate the excellent plasmonic properties of Ga nanoparticles, which along with facile processing techniques makes it an attractive alternative to the prevalent noble metal plasmonics having applications in flexible/stretchable materials and textiles. |
