An Outline of a Research Strategy

Current interests include such topics as

transport and electric properties of monocrystalline and polycrystalline materials, including thin films

effect of surface modification on charge carrier kinetics

shallow traps in various types of semiconductors

the effect of dopants on the energy and density subband gap states

The main instrumental method is the Advanced Method of Transient Microwave Photoconductivity (AMTMP). This method permits simultaneous measurement of changes in a cavity resonance frequency and a quality factor after sample illumination. These changes are proportional to changes in a real and in imaginary parts of dielectric constant according to a cavity perturbation theory. Usually (but not always) conduction electrons cause a change in a material conductivity related to a change of cavity quality factor (photoconductivity). Trapped electrons cause a change in the real part of dielectric constant related to a shift of a resonance frequency (photodielectric effect).As a result, this unique registers both free and trapped electron kinetics.

AMTMP, experimental

AMTMP, theory

Microwave Response due to Light Induced Changes in the Complex Dielectric Constant of Semiconductors

Multiple trapping rate equation simulation for various distributions of localized states in the band gap

Experimental results

  • CdSe thin film
  • Advanced Transient Microwave Photoconductivity Measurements of Polycrystalline CdSe Films
  • Si
  • GaAs
  • "Shine on you crazy diamond!..."
  • Surface effects

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