A silicon wafer (NA=10¹⁴cm⁻³,τₙ=1μsec) is first illuminated for a time t≫τₙ with light which generates Gₗₒ=10¹⁶ electron³
−sec uniformLly throughout the volume of silicon. At time t=0, the light intensity is reduced, making GL=G Lo/2 for t≥0.