DIFFERENT from current answers, please read carefully

To activate implanted dopants at the surface of a semiconductor wafer, a laser pulse may be used. Assume that the wafer can be treated as semi-infinite and that its thermal diffusivity is 0.3cm2/s. (a) The wafer is initially at 25C, and the laser pulse supplies enough energy to heat the top 0.4m of the wafer to 900C. Please plot the temperature as a function of time at a depth 5m beneath the surface. (b) At what time is the maximum temperature reached? Please solve this problem exactly, and then compare your solution to the plot to see if it is correct