7) The number of allowed electron state per unit energy range is defined by: g(s) = (2m) ¹/24/2 V 2x²h³ where Vis the volume of the lattice and m the mass of an electron. The lowest energy state of N electron is obtained by filling the N states of lowest energy. 1. Using the density of state find an expression of the number of states N with energy less than the Fermi energy &

The main feature of photo-detectors made of high energy gap semiconductors is that: O a. They have very small dark current. O b. Their absorption coefficients are quite large. O c. A large number of photons is needed to boost their resulting current. O d. Thin samples are needed for such detectors O e. NON of the given choices is correct.

3 The Fermi-Dirac distribution provides the fraction of electrons that can be found for a given electron energy and temperature of the material. Silicon is a widely use semiconductor for computer processors and GPUs, with a band gap of 1.11 eV at room temperature (293 K). a) What is the Fermi energy of Silicon at room temperature? b) Calculate the electron concentration (total number of electrons) at 0.6 eV above the fermi level (in the conduction band) of one mol of silicon (each silicon atom contributes 4 electrons).

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