What maximum light wavelength will excite an electron in the valence band of an

Question

What maximum light wavelength will excite an electron in the valence band of an insulator to the conduction band? The energy gap of the insulator is 5.10 eV. nm In what part of the electromagnetic spectrum does this wavelength lie? radio microwave infrared visible ultraviolet x-ray gamma ray The occupancy probability function shown below can be applied to semiconductors as well as to metals. P(E) = 1/e^(E - E_f)/kT + 1 In semicondüctors the Fermi energy is close to the midpoint of the gap between the valence band and the conduction band. For a certain semiconductor, the gap width is 0.56 eV. Assume that T = 295 K. (Note: In a pure semiconductor, the Fermi energy lies symmetrically between the population of conduction electrons and the population of holes and thus is at the center of the gap. There need not be an available State at the location of the Fermi energy.) What is the probability that a State at the bottom of the conduction band is occupied? What is the probability that a State at the top of the valence band is not occupied?

Explanation / Answer

a)

here by using the formula

E = h * c / lambda

lambda = h * c / E

lambda = 6.626 * 10^-34 * 3 * 10^8 / (5.1 * 1.602 * 10^-19)

lambda = 2.43 * 10^-7 m

b)

the ultraviolet

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