Math Problem Statement

The temperature at which an electron occupies an energy state 0.1 eV above the Fermi level with a probability of 0.01 is approximately ___ K.

223

253

273

303

Solution

We can use the Fermi-Dirac distribution to solve this problem. The probability that an electron occupies an energy state EE at a given temperature TT is given by:

f(E)=11+e(EEF)/(kBT)f(E) = \frac{1}{1 + e^{(E - E_F) / (k_B T)}}

Where:

  • f(E)f(E) is the probability that the energy state is occupied.
  • EEF=0.1eVE - E_F = 0.1 \, \text{eV} is the energy difference between the state and the Fermi level.
  • kBk_B is the Boltzmann constant, kB=8.617×105eV/Kk_B = 8.617 \times 10^{-5} \, \text{eV/K}.
  • TT is the temperature in Kelvin.
  • f(E)=0.01f(E) = 0.01.

We need to solve for TT when f(E)=0.01f(E) = 0.01.

Rearranging the Fermi-Dirac equation:

0.01=11+e(0.1eV)/(kBT)0.01 = \frac{1}{1 + e^{(0.1 \, \text{eV}) / (k_B T)}}

1+e(0.1eV)/(kBT)=1001 + e^{(0.1 \, \text{eV}) / (k_B T)} = 100

e(0.1eV)/(kBT)=99e^{(0.1 \, \text{eV}) / (k_B T)} = 99

Now, take the natural logarithm on both sides:

0.1eVkBT=ln(99)\frac{0.1 \, \text{eV}}{k_B T} = \ln(99)

T=0.1eVkBln(99)T = \frac{0.1 \, \text{eV}}{k_B \ln(99)}

Now, we calculate TT.

T=0.1eV(8.617×105eV/K)ln(99)T = \frac{0.1 \, \text{eV}}{(8.617 \times 10^{-5} \, \text{eV/K}) \ln(99)}

Let me compute that for you.The temperature at which an electron occupies an energy state 0.1 eV above the Fermi level with a probability of 0.01 is approximately 253 K.

Let me know if you'd like more details or have any questions!

Here are 5 related questions you might explore:

  1. What is the Fermi-Dirac distribution used for in solid-state physics?
  2. How does the probability of electron occupation change with temperature?
  3. How is the Fermi level defined in a metal at absolute zero?
  4. What is the significance of the Boltzmann constant in statistical mechanics?
  5. How does the energy band structure affect electron occupancy in semiconductors?

Tip: The Fermi-Dirac distribution is most relevant for systems where quantum effects are significant, especially at very low temperatures.

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Math Problem Analysis

Mathematical Concepts

Fermi-Dirac Distribution
Statistical Mechanics
Exponential Functions
Logarithms

Formulas

f(E) = 1 / (1 + exp((E - E_F) / (k_B T)))
T = (E - E_F) / (k_B ln(99))

Theorems

Fermi-Dirac Statistics
Boltzmann Distribution (in context of energy states)

Suitable Grade Level

Undergraduate Physics or Advanced High School Physics