Trapping of Minority Carriers in Silicon. II.n-Type Silicon

Experimental evidence of temporary trapping of holes in the volume of n-type silicon in at least two different traps is presented. The trap parameters of cross section for capture and energy level above the valence band are determined by measuring the unfilled trap density, the hole density, the rate at which holes are trapped, and the rate at which holes are released from traps. Measurement of the temperature dependence of these quantities for the deeper traps gives, in addition, the temperature variation of the cross section for capture, the energy level of the traps below the conduction band and a second determination of the trap level above the valence band. The values obtained are consistent with accepted values of the energy gap. There is evidence for a loss mechanism for holes (recombination) from the deeper traps at a rate which is found to be proportional to the square of the electron concentration.