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Dopant density (cm-³) 1021 1020 1019 1018 1017 1016 10¹5 1014 1013 10¹2, 10-4 10-3 10-¹ 10⁰ 10¹ 10² 10³ 104 Resistivity (ohm-cm) FIGURE 2-8 Conversion between resistivity and dopant density of silicon at room temperature. (After [3].) N type 10-2 P type EXAMPLE 2-3 Temperature Dependence of Resistance a. What is the resistivity, p, of silicon doped with 10¹7cm-3 of arsenic? b. What is the resistance, R, of a piece of this silicon material 1 um long and 0.1 μm² in cross-sectional area? c. By what factor will R increase (or decrease) from T = 300 K to T = 400 K? d. What As concentration should one choose if she wishes to minimize the change in (c)?