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 3× 1019 atoms/m3. The drive-in diffusion treatment is to be carried out at 1050°C for a period of4.0 h, which gives a junction depth xj of 3.0 μm. Compute the predeposition diffusion time at950°C if the surface concentration is maintained at a constant level of 2 × 1025 atoms/m3. Forthe diffusion of Al in Si, values of Qd and D0 are 3.41 eV and 1.38 × 10-4 m2/s, respectively.

Apump is used to circulate hot water in a home heating system. water enters the well-insulated pump operating at steady state at a rate of 0.42 gal/min. the inlet pressure and temperature are 14.7 lbf/in.2, and 180°f, respectively; at the exit the pressure is 60 lbf/in.2 the pump requires 1/15 hp of power input. water can be modeled as an incompressible substance with constant density of 60.58 lb/ft3 and constant specific heat of 1 btu/lb or. neglecting kinetic and potential energy effects, determine the temperature change, in °r, as the water flows through the pump.

The higher the astm grain-size number, the coarser the grain is. a)-true b)-false

Machinery that is a key part of the process and without which the plant or process cannot function is classifed as: (clo4) a)-critical machinery b)-essential machinery c)-general purpose machinery d)-none of the specified options.