Question

2. What are R-G centers and what is the R-G current?

Answer 1

R-G center recombination involves a two step process. A carrier and electron, for example, strays into the vicinity of an R-G center, an electronic level near mid-gap, and is trapped. Later comes a hole and the electron is attracted to the hole and loses more energy so it goes into the valence band annihilating the hole along with itself, this is called indirect recombination. This method releases thermal energy or produces lattice vibrations.

R-G centers are special locations within the semiconductor which are lattice defects or special impurity atoms that introduce allowed electronic levels near the center of the band gap.