Recombination Model
Recombination theory calculating the rate of electron and hole transitions through deep level traps. Application of shockley-read-hall statistics explains the generation-recombination noise observed in silicon junctions. The equations describe how a single defect level facilitates the exchange of carriers between the conduction and valence bands.
Transition Rate
Mathematical expressions define four distinct processes involving the capture and emission of electrons and holes. In the context of shockley-read-hall statistics, the net recombination rate is highest when the trap energy level lies near the middle of the bandgap. These transitions occur because the defect provides a stepping stone that reduces the energy required for a carrier to move between bands.
The rate is proportional to the concentration of defects and the occupancy of the trap states.
Carrier Lifetime
Lifetime of a charge carrier is determined by the probability of encountering an unoccupied recombination center. Designs using shockley-read-hall statistics allow engineers to estimate the leakage current in diodes and the gain in bipolar transistors.
Material Boundary
Calculations assume a uniform distribution of traps throughout the bulk of the semiconductor material. Impurities or lattice dislocations concentrated at the surface often require modified versions of shockley-read-hall statistics to maintain accuracy.
