Semiconductor physics

What is the approximate resistivity of n-type silicon with an electron density of 1×10¹⁶ cm⁻³ and an electron mobility of 1000 cm²/V·s? (Ignore holes; elementary charge 1.6×10⁻¹⁹ C)

  1. AAbout 0.06 Ω·cm
  2. BAbout 0.6 Ω·cm
  3. CAbout 60 Ω·cm
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Answer: B. About 0.6 Ω·cm

Conductivity is σ = qnμ = 1.6×10⁻¹⁹ × 1×10¹⁶ × 1000 = 1.6 S/cm, and resistivity is its inverse, ρ ≈ 0.63 Ω·cm. ρ ≈ 1/(qnμ) is the basic formula for estimating dopant concentration from wafer resistivity. In practice, conversion tables (such as ASTM standards) that include the doping dependence of mobility are used; for example, a 1–10 Ω·cm p-type wafer corresponds to boron in the 10¹⁵ cm⁻³ range.

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More Semiconductor physics questions

  1. What is the energy difference between the vacuum level and the bottom of the conduction band of a semiconductor called?
  2. In lightly doped silicon, what is the main reason mobility decreases as temperature rises?
  3. Which value is closest to the intrinsic carrier density of silicon at room temperature?
  4. Which value is closest to the atomic density of crystalline silicon?
  5. Which correctly describes a hole?