Practical No. 09: Determination of forbidden energy band gap in semiconductors.

 Practical No. 09: Determination of forbidden energy band gap in semiconductors.

• It is concluded that the reverse saturation current in a semiconductor diode increases exponentially with temperature.
• It is recommended to ensure the diode is properly immersed in the oil bath for uniform temperature distribution.

• Answer: Germanium will have more conductivity at room temperature.
  • Reason: A smaller energy band gap means electrons in the valence band need less energy to jump to the conduction band. Therefore, at a given temperature, germanium will have more electron-hole pairs available for conduction than silicon.

• Answer: The oil bath ensures uniform and gradual heating of the diode. It also prevents direct exposure to flame, which could cause sudden, non-uniform temperature changes or damage the diode.

• Answer: Yes, it does.
  • Reason: A larger forbidden energy gap means fewer charge carriers (electrons and holes) are available for conduction at a given temperature. Fewer charge carriers directly lead to higher resistivity.

• Answer: Yes, it is highly dependent on temperature.
  • Explanation: Reverse saturation current (I_s) is due to minority carriers. As temperature increases, more electron-hole pairs are generated thermally, significantly increasing the number of minority carriers. Hence, I_s increases exponentially with temperature.

• Answer: The forbidden energy gap (Eg) is the minimum energy required to excite an electron from the valence band to the conduction band. It is the energy difference between the top of the valence band and the bottom of the conduction band.