Problem 1: Consider each material at room temperature (300 Kelvin): a metal, an insulator and a semi- conductor. We meas

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Problem 1 Consider Each Material At Room Temperature 300 Kelvin A Metal An Insulator And A Semi Conductor We Meas 1 (240.67 KiB) Viewed 36 times

Problem 1: Consider each material at room temperature (300 Kelvin): a metal, an insulator and a semi- conductor. We measure the conductivity of the material and then we repeat the measurement after increasing temperature by one degree Kelvin. Suppose we see the following: • For the metal the conductance decreases slightly (by about 0.3 percent.) • For the insulator the conductance remains effectively zero (no measurable current). • For the semi-conductor the conductance increases by 3.3 percent. Part (a). First, explain these results qualitatively. Why should conductance in a metal go down slightly with temperature? Why should it go up in a semi-conductor? Part (b). Next, use the measurement given to determine the band gap of the semi-conductor. Hint: assume the increased conductance results proportionately from an increase in available charge carriers in both the valence and conduction bands.