| المؤلفون: |
Sousa FB; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil. lmalard@fisica.ufmg.br., Nadas R; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil. lmalard@fisica.ufmg.br.; FabNS, Belo Horizonte, Minas Gerais 31310-260, Brazil., Martins R; Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais 35400-000, Brazil., Barboza APM; Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais 35400-000, Brazil., Soares JS; Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais 35400-000, Brazil., Neves BRA; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil. lmalard@fisica.ufmg.br., Silvestre I; Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais 35400-000, Brazil., Jorio A; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil. lmalard@fisica.ufmg.br., Malard LM; Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil. lmalard@fisica.ufmg.br. |
| مستخلص: |
The role of defects in two-dimensional semiconductors and how they affect the intrinsic properties of these materials have been a widely researched topic over the past few decades. Optical characterization techniques such as photoluminescence and Raman spectroscopies are important tools to probe the physical properties of semiconductors and the impact of defects. However, confocal optical techniques present a spatial resolution limitation lying in a μm-scale, which can be overcome by the use of near-field optical measurements. Here, we use tip-enhanced photoluminescence and Raman spectroscopies to unveil the nanoscale optical properties of grown MoS 2 monolayers, revealing that the impact of doping and strain can be disentangled by the combination of both techniques. A noticeable enhancement of the exciton peak intensity corresponding to trion emission quenching is observed at narrow regions down to a width of 47 nm at grain boundaries related to doping effects. Besides, localized strain fields inside the sample lead to non-uniformities in the intensity and energy position of photoluminescence peaks. Finally, two distinct MoS 2 samples present different nano-optical responses at their edges associated with opposite strains. The edge of the first sample shows a photoluminescence intensity enhancement and energy blueshift corresponding to a frequency blueshift for E 2g and 2LA Raman modes. In contrast, the other sample displays a photoluminescence energy redshift and frequency red shifts for E 2g and 2LA Raman modes at their edges. Our work highlights the potential of combining tip-enhanced photoluminescence and Raman spectroscopies to probe localized strain fields and doping effects related to defects in two-dimensional materials. |
