Basic queries of semiconductor devices

In summary: Overall, the Fermi level, doping concentration, and temperature all have a significant impact on the behavior of semiconductors.
  • #1
shaikss
33
0
I have few queries regarding the below Qs.

1. How does the fermi level vary with distance under both equilibrium and non-equilibrium conditions? Is it constant or varying under equilibrium and non-equilibrium conditions?
My query>> Fermi level vary with temp. But I am not getting how to analyse how fermi level changes w.r.t distance.
2. what happens to fermi energy level when temp is increased in n-type semiconductors?
My explanation>> When temp is increased, donor electrons move from valence band to conduction band and so is the fermi level. At the same time, when the increase is temp is very high, there is a point where the affect of doping is neglible when compared to affect of increase in temp. So, the fermi level moves more deeper into the forbidden energy and so fermi level approches mid level of the energy gap and becomes intrinsic. Is this correct? Or had i missing something in my analysis?
3. When donor impurity concentration is increased, what happens to fermi level position?
My explanation>> Fermi level varies with doping concentration. fermi level moves towards the conduction band edge in case of N-type semiconductor and towards Valence band in case of P-type SC. Am I wrong at any point?
4. As the temperature is increased from 0 K, what happens tothe mobility of a moderately doped semiconductor?
My explanation>> Mobility increases to certain level afterwards it starts decreasing.

Please let me know whether my analysis is correct and correct me if I am wrong at any point.
Do tell me how fermi level vary with temperature.

Thanks!
 
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  • #2
Your analysis is mostly correct. The Fermi level does vary with temperature, and it increases as the temperature increases. This is due to an increase in the number of thermally excited electrons in the conduction band. As temperature increases, more electrons move from the valence to the conduction band, increasing the number of available electrons, which pushes the Fermi level up. As the temperature continues to increase, the Fermi level eventually reaches the middle of the energy gap (the intrinsic level) and remains there. The mobility of a moderately doped semiconductor does indeed increase with temperature, as the thermal energy gives electrons enough energy to move more freely through the lattice, leading to an increase in the mobility. However, at very high temperatures, mobility will begin to decrease, as the increased thermal vibrations of the lattice make it more difficult for electrons to move.
 

1. What are semiconductor devices?

Semiconductor devices are electronic components made from semiconductor materials, such as silicon, that have the ability to control the flow of electricity. They are used in a wide range of electronic devices, including computers, smartphones, and televisions.

2. How do semiconductor devices work?

Semiconductor devices work by using the properties of semiconductors to control the flow of electrons through a circuit. This is achieved by manipulating the concentration of charge carriers (electrons and holes) within the semiconductor material.

3. What are the most commonly used semiconductor devices?

The most commonly used semiconductor devices include transistors, diodes, and integrated circuits. These components are essential for the functioning of electronic devices and are found in almost every electronic device on the market today.

4. What are the differences between bipolar and field-effect transistors?

Bipolar transistors use both electrons and holes to conduct electricity, while field-effect transistors use only one type of charge carrier. Additionally, bipolar transistors are current-controlled, while field-effect transistors are voltage-controlled.

5. How are semiconductor devices tested and characterized?

Semiconductor devices are tested and characterized using a variety of techniques, such as electrical measurements, optical microscopy, and spectroscopy. These tests evaluate the performance and reliability of the devices, and can also provide valuable information for the design and fabrication process.

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