Why do semiconductors with wider band-gaps have higher output voltage?

In summary, the theory behind the relationship between band-gap and output voltage in semiconductors is that the band-gap acts as a restriction for the maximum voltage that can be produced. This is based on the equation V=E/q, where V is voltage, E is energy, and q is charge. Based on the textbooks "Solar Electricity" and "Principles of Solar Energy," it is determined that the maximum voltage is restricted by the band-gap, which is 1.1 electron volts for extrinsic silicon. However, when the cell is connected to a circuit and there is a load causing resistance, the voltage can increase. It is unclear what happens when this increased voltage goes through a PN junction with a 1.1e
  • #1
vw_g60t
5
0
In semiconductors it is known that the wider the band-gap the higher the output voltage, what is the theory behind this?
 
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  • #2
Band gap is a voltage. "Electron volts" is a measure of energy. Nobody knows what you're asking.
 
  • #3
Based on vw's one other PF post so far, I'm guessing he's asking about solar cell output. vw, is that correct? Can you tell us what references you have been reading about solar cell solid state physics?
 
  • #4
Voltage Through a PN junction with a 1.1 ev bandgap

berkeman said:
Based on vw's one other PF post so far, I'm guessing he's asking about solar cell output. vw, is that correct? Can you tell us what references you have been reading about solar cell solid state physics?

Hi,

I have been looking at various sources including searching the internet, bu the main textbooks i have are:

1) Markvart, T. 'Solar Electricity' 2000. Southampton
2) Goswami, Kreith, Kreider. ' Principles of Solar Energy'. 2001. Florida

I think I have the answer now, which is, based on V=E/q

as each electron has 1.6 x 10xy(-19) joules, then simply multiplying this by coulomb and by the internal p.d. of the pn junction (1.1ev in extrinsic silison) then obviously the max voltage this can produce is 1.1v restricted by the bandgap.

This leads me onto another problem:

WHEN THE CELL IS CONNECTED TO A CIRCUIT AND THERE IS A LOAD CAUSING RESISTANCE, WHICH INCREASES VOLTAGE. WHAT HAPPENS WHEN THIS VOLTAGE GOES THROUGH A PN JUNCTION OF 1.1eV??

thanks
 
  • #5
I put my contribution in an other discussion. Hope it helps for this one as well.
 

Related to Why do semiconductors with wider band-gaps have higher output voltage?

1. What is an electron volt (eV)?

An electron volt (eV) is a unit of energy commonly used in physics and chemistry to measure the energy of particles on an atomic scale. It is defined as the amount of energy gained or lost by an electron when it moves through an electric potential difference of one volt.

2. How does one convert electron volts to voltage?

To convert from electron volts (eV) to voltage, you can use the equation V = eV/q, where V is the voltage in volts, e is the charge of an electron (1.602 x 10^-19 coulombs), and q is the charge of the particle in question. For example, to convert 100 eV to voltage for a proton (q = 1.602 x 10^-19), you would use the formula V = (100 eV)/(1.602 x 10^-19) = 6.24 x 10^-17 volts.

3. What is the relationship between electron volts and joules?

Electron volts (eV) and joules (J) are both units of energy. One eV is equivalent to 1.602 x 10^-19 joules. This means that to convert from eV to joules, you can multiply the number of eV by 1.602 x 10^-19. For example, 100 eV is equivalent to 100 x 1.602 x 10^-19 = 1.602 x 10^-17 joules.

4. What is the significance of using electron volts in scientific calculations?

Electron volts (eV) are used in scientific calculations because they are a convenient unit of energy to use on an atomic scale. They are especially useful in nuclear and particle physics, where the energies involved are often on the order of millions of eV (known as megaelectron volts or MeV) or even billions of eV (gigaelectron volts or GeV).

5. Can electron volts be used to measure voltage in everyday electronics?

No, electron volts (eV) are not typically used to measure voltage in everyday electronics. The volt (V) is the more commonly used unit of voltage in the International System of Units (SI). However, in certain specialized fields such as semiconductor physics, eV may be used to measure the energy levels of electrons in materials. In everyday electronics, the voltage is usually measured in volts, millivolts, or microvolts.

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