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Optical Properties of Semiconductor Monolayer Heterostructures

Materials can have remarkably different properties when their dimensions are reduced. 2D crystals show a variety of exceptional electronic and optical properties. In particular, monolayers have triggered great interest as they can be incorporated into high-quality electronic and optoelectronic devices.

In this context, the goal of your project work will be to study optical properties of semiconductor monolayer heterostructures. The optical properties of such structures will be studied by white-light absorption and photoluminescence (PL). For the materials of interest, it is expected that the intensity and energy of their PL changes from bulk to monolayer due to a change in the electronic band structure. Furthermore, band alignment in monolayer heterostructures may lead to charge transfer processes. Time-resolved spectroscopy shall be used to investigate charge-carrier dynamics.

The attractiveness of the material system of 2D semiconductors not only arises from its remarkable properties, but also from the fact, that monolayer samples can be relatively easily prepared by the common exfoliation technique. Moreover, heterostructures of monolayer materials are perceived as the “lego” of the nanoworld, which provides vast possibilities to fabricate multilayered structures by monolayer stacking.

The required tasks for this project include sample preparation, spectroscopy, microscopy and data evaluation. In this project the supplied samples along with self-prepared nanostructures will be used to study their optical properties and charge carrier dynamics with ultrafast spectroscopy methods.

Contact: Dr. Arash Rahimi-Iman