Semiconductor physics

Which value is closest to the thermal voltage kT/q at room temperature (300 K)?

  1. AAbout 26 mV
  2. BAbout 0.26 mV
  3. CAbout 2.6 V
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Answer: A. About 26 mV

With the Boltzmann constant k ≈ 1.38×10⁻²³ J/K, T = 300 K and the elementary charge q ≈ 1.6×10⁻¹⁹ C, kT/q ≈ 0.0259 V, or about 26 mV. This important value appears in many equations, such as the diode current equation and MOSFET subthreshold characteristics.

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More Semiconductor physics questions

  1. Where in the band gap is the donor level created by phosphorus in silicon?
  2. Silicon contains both donors at 5×10¹⁶ cm⁻³ and acceptors at 2×10¹⁶ cm⁻³ (room temperature, all ionized). Which describes it correctly?
  3. Why does the carrier density of n-type silicon drop sharply when it is cooled to cryogenic temperatures?
  4. Which recombination process becomes significant at high carrier concentrations, where the released energy is given to another carrier instead of being emitted as light?
  5. 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)