# Diode I-V characteristics

Objective

Draw the I-V Characteristic of diode and compare the result with the theory.

Procedure

- Make connections

- Click on START to draw the characteristic curve.

- Analyse the data

- Plot the IV of LEDs

Discussion

The IV characteristic of an ideal PN junction diode is given by equation , where is the reverse saturation current, the charge of electron, the Boltzmann constant, the temperature in Kelvin. For a practical, non-ideal, diode, the equation is , where is the ideality factor, that is 1 for an ideal diode. For practical diodes it varies from 1 to 2. We have used a IN4148 silicon diode. The value of n for 1N4148 is around 2. We have calculated the value of by fitting the experimental data with the equation.

The voltage at which LED starts emitting light depends on its wavelength and Planck’s constant. Energy of a photon is given by . This energy is equal to the energy of an electron that overcomes the junction barrier and is given by . So Planck’s constant , where is the wavelength of light from the LED, the charge of electron and the velocity of light.

Repeat the experiment by heating the diode to different temperatures.