A Si sample with 1016 cm-3 donors is optically excited such that 1019 cm-3 electron/hole pairs are generated per second uniformly in the sample. The light causes the sample temperature to rise to 450 K. Find the quasi-Fermi levels upon shining the light on the sample. Electron and hole lifetimes are both 10 μs. Dp = 12 cm2/s, Dn = 36 cm2/s, ni = 1014 cm-3 at 450 K.

1in2 processor chip can be modelled as an isothermal plane wall of silicon, isothermal on both sides. the power input to the bottom of the plane wall, or the processing power of the chip, often called the thermal design power (tdp), is 100w. assume the periphery is adiabatic. the silicon is 400 microns thick. the temperature at the junction, or in this case on the bottom of the isothermal plane wall, is 85°c. what is the top surface temperature, assuming that the only mode of heat transfer is conduction