Which junction corresponds to sub cell 3?
Sub cell based on Ge.
Sub cell based on GaAs.
Sub cell based on GaInP.
Sub cell based on GaInAs.
To determine which junction corresponds to sub cell 3, we need to understand the order in which the sub cells are typically arranged in a multijunction solar cell.
Multijunction solar cells consist of multiple sub cells made from different materials stacked on top of each other, with each sub cell optimized to absorb light from a specific wavelength range. The sub cells are connected in series, meaning the current generated in each sub cell is combined to provide higher overall output voltage.
The order in which the sub cells are arranged is usually based on their bandgap, with the sub cell having the highest bandgap (and thus absorbing shorter wavelength light) placed at the top, and the sub cell with the lowest bandgap (and thus absorbing longer wavelength light) placed at the bottom.
Now, let's look at the bandgap of the materials mentioned:
- Germanium (Ge) has a bandgap of around 0.66 eV.
- Gallium Arsenide (GaAs) has a bandgap of around 1.42 eV.
- Gallium Indium Phosphide (GaInP) has a bandgap of around 1.9 eV.
- Gallium Indium Arsenide (GaInAs) has a bandgap of around 0.7-1.4 eV, depending on the composition.
Based on the bandgap values, we can determine the order of the sub cells in a typical multijunction solar cell:
1. The sub cell with the highest bandgap is usually based on GaInP (bandgap ~1.9 eV) and is placed at the top.
2. The next sub cell is usually based on GaAs (bandgap ~1.42 eV) and is placed below the GaInP sub cell.
3. The third sub cell is usually based on Ge (bandgap ~0.66 eV) and is placed below the GaAs sub cell.
4. The fourth sub cell is usually based on GaInAs (bandgap ~0.7-1.4 eV) and is placed at the bottom.
Therefore, in the given list, the junction that corresponds to sub cell 3 is the one based on Germanium (Ge).