Electrical Properties of pn Junction in Depletion Mode            

Procedure

Fig. 1. Basic Structure of PN Junction

Materials Required

  • pn Junction Diode
  • Power Supply
  • Multimeter
  • Connecting Wires

Procedure

  1. Setup the Circuit:
    • Connect the pn junction diode in the circuit with the power supply and multimeter as shown in the diagram.
    • Ensure the connections are secure and correct.
  2. Set Initial Parameters:
    • Set the acceptor concentration in the p-region (NA) to a desired value (e.g., 1e15 /cm^3).
    • Set the donor concentration in the n-region (ND) to a desired value (e.g., 1e15 /cm^3).
    • Adjust the applied voltage (V) to a specific value (e.g., -0.5 V).
    • Set the temperature (T) to a specific value (e.g., 300 K).
  3. Apply the Parameters:
    • Turn on the power supply and apply the set parameters to the circuit.
    • If using simulation software, enter the parameters into the simulation tool and run the simulation.
  4. Record the Data:
    • Observe and record the following characteristics:
      • Band Diagram: Note the energy bands across the pn junction.
      • Current-Voltage Characteristics: Measure and plot the I-V curve of the diode.
      • Charge Density: Determine the charge distribution across the junction.
      • Electric Field: Measure the electric field intensity in the depletion region.
      • Carrier Densities: Measure the concentration of electrons and holes.
      • log(Carrier Densities): Plot a logarithmic view of the carrier concentrations.
  5. Analyze the Data:
    • Use the recorded data to analyze the electrical properties of the pn junction:
      • Calculate the Depletion Width (W) using the charge density profile.
      • Determine the Built-in Potential (Vbi) from the band diagram.
      • Examine the Electric Field (E) distribution within the depletion region.
      • Compare the carrier densities inside and outside the depletion region.
  6. Conclude the Experiment:
    • Summarize the findings and compare them with theoretical expectations.
    • Discuss any discrepancies and possible sources of error.