Prykhodko K. Active semiconductor elements for generation in the terahertz range

The thesis is devoted to investigate of increasing of limiting operation frequencies of semiconductor devices using for generation of electromagnetic oscillations and noise in terahertz and subterahertz ranges. Development of novel solid state sources of electromagnetic oscillation and modification of existing active elements by using of graded-gap semiconductors and impact ionization effects are considered. A mathematical model of charge carrier transport in semiconductors has been developed, taking into account impact ionization and inhomogeneous composition distribution. The initial stage of impact ionization development in InGaAs, InGaN and InAlN semiconductor compounds has been studied. Possibility of obtaining noise generation in short diodes with a cathode static domain containing a graded-gap layer in the near-cathode has been researched. Possibility of ultrahigh-frequency generation has been first investigated. Energy and frequency characteristics of GaAs - GazIn1-zAs- graded gap layer- structures operating under impact ionization conditions in the graded gap anode layer of the semiconductor have been determined. A planar structure with a n+- lateral boundary based on a graded- gap GaInAs semiconductor is proposed and investigated. Frequency limit of this structure exceeds 300 GHz in fundamental frequency generation mode. The obtained results will allow to improve characteristics of the existing terahertz range sources and to create new ones. The results of noise characteristics of the static cathode domain diode indicate a possibility of using such structures in radiometric systems as а noise reference. Keywords: heterojunction, graded layer, electric field strength, impact ionization, resonant tunneling border, electromagnetic field.