# Electronic Transport

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## Informatie over het examen

Electronic Transport is a course given by professor Houssa. The last lectures are given by guest professors from the university of Antwerp/Imec and are more theoretical. The exam consists of two questions, one for each part. Mathematical detail is not required and the emphasis is more on the physical interpretation of the formulas discussed during the lectures.

## 20 juni 2018

Question 1 (Houssa)

• Describe the Hall effect and its derivation from the BTE. Discuss measurement of the Hall effect and the resistivity in a 2D (van der Pauw) geometry.

Question 2 (SorÃ©e)

• Give and explain the three main scattering mechanisms that affect the low field mobility of a nanowire transistor. Also discuss the effect of confinement on the mobility.

## juni 2018

Question 1 (Houssa)

• Explain RTA and its validity. Give the important scattering mechanisms and their temperature range.

Question 2 (Magnus)

• The probability per unit time for phonon emission is given.

- What are M, omega and nu? Explain their physical meaning.
- Without doing a calculation, derive the equivalent expression for the probability per unit time for the absorption of one phonon.
- Why does the probability for phonon emission not vanish when the temperature goes to zero?

• Take a 1D conductor in stationary state. Assume that the electrons are described by the stationary state distribution of the Drude model with relaxation time tau (the distribution is given).

- Calculate the current density J of the electrons and retrieve Ohm's law following the Drude model.

## 18 june 2014

Question 1 (Houssa)

• Discuss the temperature dependence of the conductivity, both for metals and semiconductors. What are the most important differences between the two? Is the relaxation time approximation a good approximation for describing the conductivity?

Question 2 (SorÃ©e)

• Give and explain the three main scattering mechanisms that affect the low field mobility of a nanowire transistor. Also discuss the effect of confinement on the mobility.