Laboratories

Investigating optical properties of 2D materials

Raman spectrometer based on confocal microscope

Optical setup based on confocal microscope in backscattered configuration serves for absorption (contrast reflectivity), photoluminescence and Raman spectra measurements. Excitation laser power is maintained sufficiently low to avoid damage to the sample. At the moment, two excitation laser lines are provided: 532 nm and 630 nm. A home-made confocal microscope based on cage system design is equipped with an appropriate set of filters, dichroic mirrors, polarization plates and objective lens. Collected backscattered light is guided through an optical fiber with a 50 μm core diameter, which acts as a confocal detection pinhole to a 30 cm long spectrograph equipped with a cooled electron multiplying charge coupled device – EM CCD that increases sensitivity for challenging samples with low signal levels. Triple Raman spectrometer with 300, 600 and 1800 grooves/mm diffraction gratings is used to collect the absorption, photoluminescence and Raman spectra, respectively.

Equipped with xy-translator stages, confocal setup provides both a sequential sample movement and spectrum data acquisition from the defined sample area with sub-micron resolution. In this way spatial maps of the sample are created. A software platform is developed to deliver an intuitive and user-friendly interface for data acquisition, data processing, data analysis and display. Confocal spectral imaging will be used to obtain the local spectra at each scanning pixel position.

Synthesis of 2D materials

CVD oven 

Scanning probe microscopy

Device fabrication

FET transistor