As a particle geometry deviates from that of a sphere (MW unchanged), the result on the sedimentation coefficient measured under otherwise identical conditions would be: Sedimentation coefficient increases Sedimentation coefficient decreases Sedimentation coefficient is independent of geometry Cannot be predicted without conducting the experiment

Aluminum atoms are to be diffused into a silicon wafer using both predeposition and drive-in heat treatments; the background concentration of Al in this silicon material is known to be 2.5 x 101⁹ atoms/m³. The drive-in diffusion treatment is to be carried out at 1050°C for a period of 4.0 h, which gives a junction depth x; of 3.0 μm. Compute the predeposition diffusion time at 950°C if the surface concentration is maintained at a constant level of 2 x 1025 atoms/m³. For the diffusion of Al in Si, values of Qd and Do are 3.41 eV and 1.38 x 10-4 m²/s, respectively. min