| Description |
The study of lower dimensional materials in the past few decades has been motivated by both the emergence of new physical properties due to quantization of excitations in the system, and the possibility of engineering the physical properties of such systems for potential applications. The role of defects, substrate interactions, and sample quality becomes more important at such length scale. Here, we present optical and electrical characterization of two such material systems; metallic single wall carbon nanotubes (SWNTs), and few layered Molybdenum di-Sulphide.
We are able to fabricate nearly defect free metallic SWNTs, and show a strong non-adiabatic electron-phonon interaction in this ultra clean material system. By simultaneous electrical and optical measurements, we are able to demonstrate the role of a finite bandgap on the electron-phonon interaction in these quasi-metallic CNTs.
We also study exfoliated few layer MoS2, a transition metal dichalcogen, with very desirable optical properties. A 30 fold enhancement in the photoluminescence signal for MoS2 is reported with a gentle oxygen plasma treatment, due to a decoupling of individual layers, leading to transition from indirect to direct band. Evidence is given for the creation of long lived exciton states, possibly localized by defect sites created during the plasma treatment process.
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