A fully computer controlled, low cost STM

Summary If one examines the components of a scanning tunneling microscopy system, one finds, that for a great part the computer determines the abilities of it. Once a stable mechanical setup is constructed, it depends on the control part, which features the whole system shows and how convenient one can work with it. Here we present a scanning tunneling microscope which is, as far as possible, computer controlled and can be fully operated from a user surface on the computer. This has been achieved by the use of a two computer concept. The mechanics, electronics and software were self-developed; all other components were selected under the aspect of costs resulting in a low priced and yet high performance system.     

Far-infrared magnetospectroscopy on epitaxial zero-gap and wide-gap semiconductor layer systems

Far-infrared magnetotransmission measurements have been performed on MBE-grown HgTe and CdTe epilayers. The results on the HgTe samples can be understood by the standard Pidgeon-Brown model for bulk HgTe. For the CdTe layers, transitions were only observed under illumination by visible light. The spectra are dominated by the 1s2p transition of the shallow hydrogen-like impurity. These transitions are persistent with a life time of the order of magnitude of one second.