As a part of producing MOSFET transistors, a p-type silicon (Si) wafer containing boron (B) dopants at a concentration of 1x1019 atoms/cm3 is being processed to create a PN junction by doping the wafer with phosphorous (P) atoms using a P-producing gas. Assume that the wafer does not contain P prior to the diffusion process. The solubility of P in Si at 1000°C is 1x1020 atoms/cm3. It is determined that the PN junction depth of 1 um was produced after 60 minutes at 1000°C. The activation energy for estimating the diffusion coefficient of P in Si is 2.5x105 J/mole. Based on this result, estimate the pre-exponential constant for the diffusion coefficient of P in Si at 1000°C in cm2/s.