Exam 41: Conduction of Electricity in Solids

A certain material has a resistivity of 7.8 *10³ $\Omega$ .m at room temperature, and its resistivity decreases as the temperature is raised by 100 $\degree$ C. The material is most likely:

Switch S is closed to apply a potential difference V across a p-n junction as shown. Relative to the energy levels of the n-type material, with the switch open, the electron levels of the p-type material are:

At room temperature, kT is about 0.0259 eV. The probability that a state 0.50 eV above the Fermi level is occupied at room temperature is:

The Fermi energy of a metal depends primarily on:

Donor atoms introduced into a pure semiconductor at room temperature:

When a forward bias is applied to a p-n junction the concentration of electrons on the p side:

The density of states for a metal depends primarily on:

Compared to the number of conduction electrons in pure silicon, the number of conduction electrons in doped silicon is:

The gap between the valence and conduction bands of a certain semiconductor is 0.85eV. When this semiconductor is used to form a light emitting diode, the wavelength of the light emitted:

A light emitting diode emits light when:

Possible units for the density of states function N(E) are:

Acceptor atoms introduced into a pure semiconductor at room temperature:

Application of a forward bias to a p-n junction:

Electrons in a full band do not contribute to the current when an electric field exists in a solid because:

If the density of states is N(E) and the occupancy probability is P(E), then the density of unoccupied states is:

For an unbiased p-n junction, the energy at the bottom of the conduction band on the n side is:

The energy level diagram shown applies to:

In an unbiased p-n junction:

For a pure semiconductor at room temperature the temperature coefficient of resistivity is determined primarily by:

The energy gap between the valence and conduction bands of an insulator is of the order: