Temperature dependent carrier lifetime studies of Mo in crystalline silicon

The capture cross sections of both electrons σ_n and holes σ_p were determined for interstitial molybdenum in crystalline silicon over the temperature range of-110 to 150 °C. Carrier lifetime measurements were performed on molybdenum-contaminated silicon using a temperature controlled photoconductance instrument. Injection dependent lifetime spectroscopy was applied at each temperature to calculate σ_p and σ_n. This analysis involved a novel approach that independently determined the capture cross sections at each temperature assuming a known defect density and thermal velocity. Since the energy state is in the lower half of the bandgap, the determination of σ_p is unaffected by the defect energy at all temperatures, and σ_p is found to decrease with temperature in a fashion consistent with excitonic Auger capture. At temperatures below 0 °C, the determination of σ_n is also unaffected by the defect energy due to the suppression of thermal emission, and σ_n decreases with temperature as well. It is shown that a projection of σ_n to higher temperature suggests the defect has an energy of 0.375 eV above the valance band edge of silicon.