2. Predeposition A 1mm thick silicon wafer is doped with antimony (Sb) uniformly to the level of 2e15 cm. Then, the wafer is exposed to a constant SbCl atmosphere for 30 minutes, which is the predeposition process. During this time the surface concentration of Sb is maintained at 48 atomic ppm by the equilibrium with the gas. After this step, the furnace atmosphere is changed to seal the surface against Sb loss and drive-in diffusion is started. The entire process (predeposition and drive-in diffusion) is carried out at 1200C. a) Is Sb an n-type dopant or p-type dopant in Si? Explain why. b) Please convert the surface concentration 48 atomic ppm into number density Cn. c) At the end of predeposition, please calculate the Sb concentration in number density at a depth of 8 microns. d) Calculate the Sb number dose (in cm) passed into the wafer during the predeposition step.