Effects of Temperature on Germanium Conductivity & Energy Gap

In summary, the conductivity of pure germanium increases by 50% when the temperature is increased from 20 degree C to 30 degree C. The energy gap E_g between the conduction and the valence bands of germanium is unknown. For silicon, E_g = 1.1eV. It is requested to find the percentage change in conductivity for the same temperature change. The key to solving this problem is to relate the conductivity to the number of electrons in the conduction band as a function of temperature.
  • #1
Larsson
28
0
The conductivity of pure germanium increases by 50% when the temperature is increased from 20 degree C to 30 degree C. What is the energy gap E_g between the conduction and the valence bands of germanium?

b) For silicon E_g = 1.1eV, what is the percentage change in the conductivity for the same temperature change?

It would be nice if someone could take a few minutes to explain this.
 
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  • #2
The standard procedure here is that you show what you've done so far and then you get help.

You need to relate the conductivity to the number of electrons in the conduction band as a function of temperature. That should give you a starting point.
 

1. How does temperature affect the conductivity of Germanium?

The conductivity of Germanium increases with increasing temperature. This is due to the increase in thermal energy, which allows more electrons to break free from their bonds and contribute to the flow of electric current. However, at very high temperatures, the conductivity decreases due to the scattering of electrons by phonons.

2. What is the energy gap of Germanium at different temperatures?

The energy gap of Germanium decreases with increasing temperature. This is because as the temperature increases, more electrons are excited from the valence band to the conduction band, reducing the energy gap between the two bands.

3. How does the energy gap of Germanium change with temperature?

The energy gap of Germanium follows an exponential relationship with temperature. As the temperature increases, the energy gap decreases at a rate of approximately 2.4 meV/K. This relationship is known as the Varshni equation.

4. What are the practical applications of studying the effects of temperature on Germanium conductivity and energy gap?

The knowledge of how temperature affects the conductivity and energy gap of Germanium is important in the design and development of electronic devices. Germanium is often used as a semiconductor material in transistors, diodes, and solar cells. Understanding its behavior at different temperatures can help improve the performance and efficiency of these devices.

5. Does Germanium behave differently from other semiconductor materials at high temperatures?

Yes, Germanium behaves differently from other semiconductor materials at high temperatures. Unlike Silicon, which has a negative temperature coefficient of resistance, the resistance of Germanium decreases with increasing temperature. This is due to the decrease in energy gap and the increase in conductivity at high temperatures.

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