Bilyovsкiy P. Effects of space redistribution of "hot" carriers sn semiconductors and heterostructures

The thesis is devoted to investigation of processes occurring with strongly non-equilibrium charge carriers in the bulk germanium crystals and n-InGaAs/GaAs heterostructures with quantum wells under the conditions of heating carriers by a high electric field. There have been studied instabilities arising under these conditions as well as formation of spatially non-uniform structures such as high-field domains or current filaments. Measurements of both the electric field distribution along a sample and infrared emission intensity revealed the thermal-diffusion autosolitons arising in the form of current filaments in the Ge crystals which were predicted earlier theoretically. There has been shown experimentally that such autosolitons arise in a weakly heated plasma with a high carrier concentration. In the case of plasma with a small carrier concentration and under strong heating up, the transverse autosolitons arise in the form of field domains. It is obtained that in the n-InGaAs/GaAs heterostructures with quantum wells under the lateral electric field, the static high field acoustoelectric domains may arise which cause the N-like behavior of their current-voltage characteristics. Using the double voltage pulse method, it is shown that decaying current oscillation, observed in the n-InGaAs/GaAs heterostructures, generated as a result of reflection of an acoustic flux by the anode contact. Also, it is shown that in the heterostructures with the double tunnel-coupled quantum wells a spatial transfer of heated electrons from the wider quantum wells into the narrower ones results in a sharp increase of intensity of the far infrared emission. An additional contribution of the direct radiative intersubband transitions of electrons in the narrower well can be responsible for this phenomenon.