Surface state capture cross sections at Si/electrolyte interfaces determined by combined microwave reflection/photocurrent measurements

摘要

The change in reflected microwave power dut to the photoinduced change of the sample's average conductivity of measured.The resulting microvave reflection signal is proporational to the change of hte interal over the excess carrier profile in the semiconductor sample.With a relation between this profile and the excess charge carrier concentration at the surface,the measured change in reflexted microvave power is a measure for the change in surface concentration fo excess accrriers.With this link simultaneously recorded microvave reflection signal and photocurrent are combined to separate the surface recombinatio velocity from the charge transfer constant using a model ofr the microwave reflection signal containin these two parameters explicitly.or n-Si (4-5x10~14 cm~-3)in contact with dried propylene carbonate (PC)containing 0.1 M tetrabutylamonium perchlorate (TBAP) and 10 mM ferrocene/ferrocenium,thesetwo quantities are measured under periodic illumination as a sunction of the applied potential.The approximation of hte separated surface recombination velocity with a potential dependent Shockley-Read-Hall-formalism yields the capture cross sections for electrons (4 x 10~16 cm~3s~-1)and holes (4 x10 ~-18cm~3s~-1)of the relevant surface recombination levels.