For the predeposition heat treatment of a semiconducting device, gallium atoms are to be diffused into silicon at a temperature of 1150°c for 2.5 h. if the required concentration of ga at a position 2 μm below the surface is 8 x 1023 atoms/m3, compute the required surface concentration of ga. assume the following: (i) the surface concentration remains constant (ii) the background concentration is 2 x 1019 ga atoms/m3 (iii) preexponential and activation energy values are 3.74 x 10-5 m2/s and 3.39 ev/atom, respectively. express your answer in atoms/m3 in engineering format to three significant figures.