How Much Flux is Absorbed by a Silicon Wafer?

In summary, absorption in a silicon wafer is the process of light being absorbed by the silicon material, transferring its energy to generate heat. It is important in solar cells as it converts light energy into electrical energy. The thickness of the wafer affects absorption, with a thicker wafer allowing for more light to be absorbed but also increasing costs. The material properties, surface texture, and anti-reflective coatings all influence absorption. To increase absorption, the material properties can be optimized, surface texturing and anti-reflective coatings can be applied, and multiple layers of silicon can be used.
  • #1
thephysicsman
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Homework Statement



A silicon wafer that is 200 um thick has no front reflection, 30% back reflection and absorption coefficient [tex]\alpha=39.9 cm^{-1}[/tex]. What is the flux absorbed?

Homework Equations



Beer's absoorption law:

[tex]\Phi(x) = \Phi_0 e^{-\alpha x}[/tex]

The Attempt at a Solution



[tex]\Phi(0.02 cm) = \Phi_0 e^{-39.9 cm^{-1} \cdot 0.02} = 0.45 \cdot \Phi_0[/tex]

This means that the absorbed flux is [tex]0.55 \cdot \Phi_0[/tex]

Then we take into consideration the reflection. 30% out of the remaining 45% of [tex]\Phi_0[/tex] is reflected, that is 13.5%. 55% of this is absorbed, that is 0.55*0.135 = 7.4%.

In total, 55% + 7.4% = 62.4% is absorbed.

Is this correct?
 
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  • #2


Yes, your solution is correct. To summarize, the flux absorbed is 62.4% of the original flux (\Phi_0). This can also be written as \Phi_{abs} = 0.624 \cdot \Phi_0. This calculation takes into account both the absorption coefficient (\alpha) and the reflection coefficient (30%). Good job!
 

Related to How Much Flux is Absorbed by a Silicon Wafer?

1. What is "absorption" in a silicon wafer?

Absorption in a silicon wafer refers to the process of light being absorbed by the silicon material. This means that the energy from the light is transferred to the silicon atoms, causing them to vibrate and generate heat.

2. Why is absorption important in a silicon wafer?

Absorption is important in a silicon wafer because it is the primary mechanism for converting light energy into electrical energy in solar cells. The more light that is absorbed, the more electrical energy can be generated.

3. How does the thickness of a silicon wafer affect absorption?

The thickness of a silicon wafer affects absorption in two ways. First, a thicker wafer allows for more light to be absorbed, resulting in higher efficiency. However, a thicker wafer also means more material and higher costs, so there is a trade-off between absorption and cost.

4. What factors influence absorption in a silicon wafer?

The main factors that influence absorption in a silicon wafer are the material properties of the silicon, such as its bandgap and doping levels, and the wavelength of the incident light. Additionally, the surface texture and anti-reflective coatings can also affect absorption.

5. How can the absorption rate of a silicon wafer be increased?

The absorption rate of a silicon wafer can be increased by optimizing the material properties, such as adjusting the doping levels or using a different type of silicon. Surface texturing and anti-reflective coatings can also be applied to increase absorption. Additionally, using multiple layers of silicon can also improve absorption by allowing for a wider range of light wavelengths to be absorbed.

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