As a part of producing mosfet transistors, a p-type silicon (si) wafer containing boron (b) dopants at a concentration of 1x10^19 atoms/cm^3 is being processed to create a pn junction by doping the wafer with phosphorous (p) atoms using a p-producing gas. assume that the wafer does not contain p prior to the diffusion process. the solubility of p in si at 1000°c is 1x10^20 atoms/cm^3. it is determined that the pn junction depth of 1 um was produced after 60 minutes at 1000°c. the activation energy for estimating the diffusion coefficient of p in si is 2.5x10^5 j/mole. based on this result, estimate the pre-exponential constant for the diffusion coefficient of p in si at 1000°c in cm^2/s.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

If a particle moves along a path such that r : (3 sin t) m and ? : 2t rad, where t is in seconds. what is the particle's acceleration in m/s in 4 seconds? a)- 16.43 b)- 16.29 c)- 15.21 d)- 13.79

Give heat transfer applications for the following, (i) gas turbines (propulsion) ) gas turbines (power generation). (iii) steam turbines. (iv) combined heat and power (chp). (v) automotive engines