Electronics and Communication Engineering Microelectronics VLSI Experiments

Variation of Fermi Energy Level and Carrier Concentration with Temperature            

Procedure

  • Gather the required equipment:
    • Semiconductor sample (e.g., silicon or germanium)
    • Temperature-controlled chamber (e.g., cryostat or furnace)
    • Four-point probe setup
    • Digital multimeter
    • Data acquisition system
    • Graphing software
    • Protective equipment (gloves, safety glasses)
Semiconductor intrinsic carrier concentration versus temperature

Fig. 1. The calculated defect formation energy of Mg substitution for Ga as a function of Fermi energy

  • Set up the circuit for forward bias:
    • Connect the anode of the diode to the positive terminal of the power supply.
    • Connect the cathode of the diode to one terminal of the ammeter.
    • Connect the other terminal of the ammeter to the negative terminal of the power supply.
    • Connect the voltmeter across the diode to measure the voltage drop.

Procedure

Fig. 2. Transport properties and doping evolution of the Fermi surface in cuprates

  1. Preparation:
    • Ensure the semiconductor sample is clean and properly mounted in the four-point probe setup.
    • Verify that the temperature-controlled chamber is functioning correctly.
  2. Initial Measurements:
    • Record the initial temperature of the semiconductor sample.
    • Measure and record the resistance of the semiconductor sample at this temperature.
  3. Temperature Variation:
    • Gradually increase the temperature of the semiconductor sample in predefined steps (e.g., 10°C intervals).
    • Allow the sample to stabilize at each temperature before taking measurements.
    • At each temperature, measure the resistance of the sample using the digital multimeter.
  4. Data Collection:
    • Record the temperature and corresponding resistance values in a data table.
  5. Analysis:
    • Plot the resistance versus temperature data to determine the relationship between temperature and carrier concentration.
    • Analyze how the Fermi energy level shifts with temperature based on the observed changes in resistance.
  6. Conclusion:
    • Summarize the findings regarding the variation of the Fermi energy level and carrier concentration with temperature.
    • Discuss any deviations from theoretical expectations and potential sources of error.