Group WG1 will be led by the project leader prof. Wojciech Knap, who is a world-class expert in this area with a vast network of research cooperation. The group will focus on THz plasma instabilities, graphene and other 2D materials, Dirac matter, HgCdTe and based on other topological insulators future THz systems. Timeliness and novelty of the proposed research comes from combination of recently developed fields of research: Terahertz related science, Science of nanostructures, Topological insulators and graphene-like materials science (Dirac Matter). Plasma instabilities in systems behaving like topological insulators and other 2D and 3D systems with Dirac fermions have not been studied until now. Approach proposed in this project is pioneering because it will explore topological phase transitions and topological phases of matter by continuous tuning of band parameters with pressure, electric field and/or temperature. For the first time we will combine very strong modelling with very precise characterization by electronic transport measurements as well as by THz spectroscopy. In addition, understanding of the mechanism of instabilities in 2D Dirac Fermions systems should allow to design future semiconductor devices (emitters and detectors). The massless Dirac fermions have been demonstrated in graphene, HgCdTe, PbSnTe and other materials. However, specific technological obstacles in device fabrication in these materials still limit their applications. We hereby propose a research on robust, well known technology of a traditional III-V semiconductors such as InAs, GaSb, AlSb, in which charge carriers mimic pseudo-relativistic DF particles with zero rest-mass. Our results will pave a route to the pseudo-relativistic electronics on the basis of a well-known and mature III-V semiconductor technology and have important impact on innovative THz component that will be developed by WG3 and WG4 groups.