Electrical peculiarities in GaAs and Si based low dimensional structures

A brief summary of unusual vertical electrical behaviour obtained in GaAs/InAs/GaAs quantum well and quantum dot structures, Si/Ge/Si and Si/SiGe/Si structures containing nanometer size amorphous thin layers or quantum wells, SiC/Si and Fe2Si/Si structures containing nanocrystals, and porous Si/crystalline Si structures, is presented. The unusual behaviour are connected either with defects (interface, bulk or band tail energy states), or quantum mechanical effects.