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?
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Transcribed Image Text:7.7 The measured thermal conductivity of germanium at 300°K is
0.63 W/°K, 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 4x 10
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/°K. How far below the conduction-band edge does the Fermi
level lie?
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