Pulsed Far-Infrared Experiments on Dynamical Properties in Semiconductor Systems

摘要

The thesis describes an experimental study of different dynamical properties in semiconductor systems in which an excitation source has been used consisting of a pulsed far-infrared (FIR) laser. Three independent physical phenomena have been studied. The first concerns the excitation and recombination of the electron donor system, the second involves the spin-lattice relaxation of excited spins under electron paramagnetic resonance conditions (EPR) and the third is about electron transport through a tunnelling-structure under the influence of FIR radiation. In chapter 2 a description is presented of the FIR pulse laser including its specific properties. Chapter 3 considers time-resolved photoconductivity measurements with nanosecond resolution to study the recombination dynamics of photoionized shallow donor impurities in semiconductor materials. Chapter 4 considers pulsed EPR in dilute magnetic semiconductors. Measurements have been performed on crystals consisting of CdTe in which a small part of the Cd(2+) ions is replaced by paramagnetic Mn(2+) ions. Finally, in chapter 5 an experimental study is described concerning the influence of FIR radiation on the transport properties through a tunnel structure with two potential barriers.