Far-Infrared Spectroscopy of Two-Dimensional Electronic Systems with Tunable Charge Density

Abstract

Mesoscopic electronic systems, i.e. systems in the intermediate regime between totally classical and totally quantized behavior are very often studied in two-dimensional electronic systems (2 DES). 2 DES can be realized in semiconductor heterostructures or in metal-oxide-semiconductor (MOS) systems. They have attracted a great interest in the last decade [1]. This interest arose from many proposed and realized technical applications and — in an interacting way — also from fundamental physical investigations. In these systems many of the interesting physical properties can be tailored during the fabrication process and, for a particular sample, varied over a wide range via electric or magnetic fields, stress, temperature, etc. This allows very detailed studies of fundamental physical properties and of interactions that are unique to the 2 D system. For the investigation of mesoscopic effects it is advantageous that laterally confined electron systems in 2D samples can be tuned, e.g. via a gate voltage, from a macroscopic systems through the mesoscopic regime into the quantized regime. Further, a very sensitive and reproducible adjustment of e.g. the Fermi energy or other parameters is easily possible.