The penetration depth of light in a semiconductor is:

The helium–neon laser differs from Maiman’s ruby laser principally in:

For an abrupt pn junction, extrapolating a plot of 1/C_dep² versus reverse bias back to 1/C_dep² = 0 yields:

Silver has a Fermi energy E_F = 5.5 eV. Take m = 9.11 × 10⁻³¹ kg and 1 eV = 1.602 × 10⁻¹⁹ J. (a) Using ½mv² = E_F, calculate the Fermi speed v_F. (b) A classical gas particle at 300 K would have an average kinetic energy of (3/2)kT = 0.0388 eV; calculate the speed corresponding to that energy the same way. (c) Compare the two speeds and explain in one or two sentences what the comparison reveals about why the classical electron gas model fails for metals. Show your work.

A junction is fabricated with very heavy doping on both sides, giving a correspondingly narrow depletion region. Under increasing reverse bias it will most likely break down by:

Diamond has a forbidden energy gap of about 5.5 eV. At room temperature it behaves as:

In the free-electron model, increasing the conduction electron concentration of a metal raises its Fermi energy.

In the high-temperature Dulong–Petit limit the molar heat capacity of a solid approaches 3R, with R = 8.314 J mol⁻¹K⁻¹. The energy required to raise the temperature of 2.0 mol of such a solid by 50 K is closest to:

A microwave oven operates at 2.45 GHz because at that frequency water:

In a p-type silicon sample the minority-carrier (electron) mobility is μ_e = 1000 cm²V⁻¹s⁻¹ and the minority-carrier lifetime is τ = 2.0 μs. Take kT/e = 0.0259 V at 300 K. (a) Use the Einstein relation to find the electron diffusion coefficient D_e in cm²/s. (b) Compute the diffusion length L = √(D_eτ) and express it in μm. (c) A solar cell built from this material is 50 μm thick. State in one sentence whether carriers generated near the back surface are likely to be collected, and why. Show your work.