Chapter 8
Transport
Um über den Temperaturverlauf des Widerstandes Rechenschaft geben zu können,
müssen andere Abweichungen von der strengen Periodizität entscheidend sein,
nämlich diejenigen, welche von den thermischen Eigenschwingungen des Kristalls
herrühren.
In order to be able to account for the temperature dependence of the resistivity, other
deviations from the strict periodicity must be decisive, namely those which result from
the thermal vibrations of the crystal.
F. Bloch, 1928 [61]
Abstract The physics of transport in semiconductors is treated foremost for charge transport. Band
transport and scattering, mobility, low field and high field effects as well as polarons and hopping
transport are covered. A short section mentions ionic transport before heat conduction and coupled
heat and charge transport including thermopower and Peltier effect are discussed.
8.1 Introduction
Charge and heat energy can be transported through the semiconductor in the presence of appropriate
(generalized) forces. Such a force can be an electric field or a temperature gradient. Both transport
phenomena are coupled since electrons transport energy and charge simultaneously through the crystal.
First, we will treat the charge transport as a consequence of a gradient in the Fermi level, then the heat
transport upon a temperature gradient and finally the coupled system, i.e. the Peltier and Seebeck
effects. Detailed treatments of carrier transport can be found in [713, 714].
Practically all important semiconductor devices are based on the transport of charge, such as diode,
transistor, photodetector, solar cell and laser.
Carriers move in the semiconductor driven by a gradient in the Fermi energy. We distinguish
• drift, as a consequence of an electric field E,
• diffusion, as a consequence of a concentration gradient ∇n or ∇ p.
In inhomogeneous semiconductors for which the position of the band edges is a function of position,
another force occurs. This will not be treated here, since later (cf. Chap. 12) it will be included as an
additional, internal electric field.
© Springer Nature Switzerland AG 2021
M. Grundmann, The Physics of Semiconductors, Graduate Texts in Physics,
https://doi.org/10.1007/978-3-030-51569-0_8
223
Transport
Um über den Temperaturverlauf des Widerstandes Rechenschaft geben zu können,
müssen andere Abweichungen von der strengen Periodizität entscheidend sein,
nämlich diejenigen, welche von den thermischen Eigenschwingungen des Kristalls
herrühren.
In order to be able to account for the temperature dependence of the resistivity, other
deviations from the strict periodicity must be decisive, namely those which result from
the thermal vibrations of the crystal.
F. Bloch, 1928 [61]
Abstract The physics of transport in semiconductors is treated foremost for charge transport. Band
transport and scattering, mobility, low field and high field effects as well as polarons and hopping
transport are covered. A short section mentions ionic transport before heat conduction and coupled
heat and charge transport including thermopower and Peltier effect are discussed.
8.1 Introduction
Charge and heat energy can be transported through the semiconductor in the presence of appropriate
(generalized) forces. Such a force can be an electric field or a temperature gradient. Both transport
phenomena are coupled since electrons transport energy and charge simultaneously through the crystal.
First, we will treat the charge transport as a consequence of a gradient in the Fermi level, then the heat
transport upon a temperature gradient and finally the coupled system, i.e. the Peltier and Seebeck
effects. Detailed treatments of carrier transport can be found in [713, 714].
Practically all important semiconductor devices are based on the transport of charge, such as diode,
transistor, photodetector, solar cell and laser.
Carriers move in the semiconductor driven by a gradient in the Fermi energy. We distinguish
• drift, as a consequence of an electric field E,
• diffusion, as a consequence of a concentration gradient ∇n or ∇ p.
In inhomogeneous semiconductors for which the position of the band edges is a function of position,
another force occurs. This will not be treated here, since later (cf. Chap. 12) it will be included as an
additional, internal electric field.
© Springer Nature Switzerland AG 2021
M. Grundmann, The Physics of Semiconductors, Graduate Texts in Physics,
https://doi.org/10.1007/978-3-030-51569-0_8
223