1. Terahertz Photonics Laboratory, Center for Physical Sciences and Technology (FTMC) 1 , Sauletekio al. 3, LT-10257 Vilnius, Lithuania
2. Laboratory of Semiconductor Characterization, Institute of High Pressure Physics PAS (UNIPRESS) 2 , ul. Sokołowska 29/37, 01-142 Warsaw, Poland