# 1. The diffusion rate of A in B was studied at 500°C and 850°C. It was reported that, for the same diffusion time, the depths of penetration xi and x2 in the two experiments were in the ratio of 1: 4. Show that the activation energy of A in B is 57 kJ/mol. 2. An amount Q of a dopant is deposited on the surface of a silicon substrate. During a subsequent anneal without the dopant in the atmosphere the concentration c of the donant as a function of depth x and time t is given by c= (0 VDI exp(-x2/4D Show that this is solution of Fick’s second law, where D is independent of concentration. 3. The activation barrier for iump is 100 kJ/mol. Calculate the rate at which a kacancy iumps in copper at 20°C.

X