Steblova O. Electron transport and electron field emission from semiconductor nanocomposite structures

The thesis is aimed to establish the main mechanisms of the electrical conductivity of Si enriched SiOx films and nanocomposite SiO2(Si) films, containing Si nanocrystals in dielectric SiO2 matrix. The main mechanisms of current transport through the investigated films are the trap conductivity with variable hopping lengths (Mott's mechanism), the space charge limited current, and the Pool-Frenkel and the Fowler-Nordheim tunneling. The conditions of the thermal and laser anneals for transformation of Si enriched SiOx (x < 2) films into the nanocomposite SiO2(Si) films. The influence of low-temperature anneals (450 C) in H2 atmosphere and in a vacuum, on the electrical conductivity of SiOx(Si) films has been studied in detail. The electron field emission from silicon nanotips coated with SiOx and SiO2(Si) ultrathin films were investigated. The efficient electron field emission has been revealed. In case of some specific structure parameters the resonance peaks on emission I-V characteristics were observed. The emission peaks on I-V characteristics were explained by the model based on the phenomenon of resonance tunneling of electrons. The influence of light on the peculiarities of the electron field emission from the Si-Ge nanoislands has been determined. The regions with negative differential resistance on the emission I-V characteristics in some samples have been observed. They appear in a strong electric field due to the quantum levels in a triangular potential well in silicon at the Si-vacuum interface.