7.7 The measured thermal conductivity of germanium at 300°K is0.63 W/°K, in a range where acoustic phonon scattering dominates.(a) What fraction of this thermal conductivity is caused by free electronsif the free-electron density is 1017 cm-³ and the electron mobility is 4x 10cm2/V-sec?(b) What must the concentration of free electrons in germanium at 300°Kbe in order for the electronic contribution to the thermal conductivity to beequal to the lattice contribution?(c) The thermoelectric power corresponding to (a) is measured to be0.46 mV/°K. How far below the conduction-band edge does the Fermilevel lie?

Given; Thermal conductivity at room temperature,K=0.63W/KLorentz number,…

7.7 The measured thermal conductivity of germanium at 300°K is 0.63 W/ºK, in a range where acoustic phonon scattering dominates. (a) What fraction of this thermal conductivity is caused by free electrons if the free-electron density is 10¹7 cm-3 and the electron mobility is 4×10³ cm²/V-sec? (b) What must the concentration of free electrons in germanium at 300°K be in order for the electronic contribution to the thermal conductivity to be equal to the lattice contribution? (c) The thermoelectric power corresponding to (a) is measured to be 0.46 mV/ºK. How far below the conduction-band edge does the Fermi level lie?

7.7 The measured thermal conductivity of germanium at 300°K is 0.63 W/ºK, in a range where acoustic phonon scattering dominates. (a) What fraction of this thermal conductivity is caused by free electrons if the free-electron density is 10¹7 cm-3 and the electron mobility is 4×10³ cm²/V-sec? (b) What must the concentration of free electrons in germanium at 300°K be in order for the electronic contribution to the thermal conductivity to be equal to the lattice contribution? (c) The thermoelectric power corresponding to (a) is measured to be 0.46 mV/ºK. How far below the conduction-band edge does the Fermi level lie?