| Abstract [eng] |
This work presents THz excitation spectroscopy technique where various semiconductors and their structures are investigated. Until now this methodology was mostly used to investigate A3B5 direct bandgap semiconductors. It was shown that the conduction band subsidiary valley position can be determined from THz excitation spectra. The generation mechanism is related to semiconductor properties and the ballistic nature of excited carriers. Similar principles were used to investigate heterostructures, where their band offset parameter is important for engineering novel opto- and micro- electronic devices. The THz excitation spectroscopy was adapted to determine such a parameter and later the investigation of GaAsBi/GaAs and GaInAsBi/InP heterostructures was completed. Also, indirect band gap and layered crystals were investigated by THz excitation spectroscopy. Here germanium and transition metal dichalcogenides showed that it is possible to determine the direct band gap of such materials, while conduction band subsidiary valley position and lower lying valence band position were determined in GaSe crystals. Lastly, thin layers of semimetal bismuth were investigated, where THz generation mechanism depended on the crystallinity of the layer. |
