Trapping of Minority Carriers in Silicon. I.P-Type Silicon

Abstract

Experimental evidence of temporary trapping of electrons in the volume of $p$-type silicon in two different traps is presented. The evidence is shown to lead to a multiple trapping model the kinetics of which explains the data. The trap parameters are determined by the fit of experimental data to the theory. The trap density, energy level, cross section for capture, $S$, and the time which an electron spends in a trap, ${\tau }_g$, are determined for both traps. For the deeper traps, $S{\tau }_g$, a property of the trap itself, is shown to have the probable value 0.81±0.25×${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$ sec with ${\tau }_g\cong 0.3$ sec for all specimens examined. In low-resistivity crystals there is evidence for a loss mechanism for electrons (recombination) from the deeper traps at a rate found proportional to the square of the hole concentration. The deep-trap concentration is found to be roughly proportional to the sample conductivity.