3. (1 charge 5-poits) A semiconductor is uniformly illuminated, and generated 1015/cm3 excess carrier. If we turn off the source of illumination, a) what will be the concentration of charge carrier at t 1 us and at 10us after the illumination turned off. The carrier life time τ-10's b) ) calculate the conductivity of the sample before turning the light off, and after 10 us 3. (1 charge 5-poits) A semiconductor is uniformly illuminated, and generated 1015/cm3 excess carrier. If we turn off the source of illumination, a) what will be the concentration of charge carrier at t 1 us and at 10us after the illumination turned off. The carrier life time τ-10's b) ) calculate the conductivity of the sample before turning the light off, and after 10 us