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A solar cell is a junction diode. A very thin layer of p-type semiconductor is grown on a…
A solar cell is a junction diode. A very thin layer of p-type semiconductor is grown on a relatively thicker n-type semiconductor, having a few finer electrodes on the top of the p type semiconductor layer.
These electrodes do not obstruct light from reaching the thin p-type layer. Just below the p-type layer, there is a p-n junction. We also provide a current-collecting electrode at the bottom of the n-type layer.
Similarly, the holes in the depletion can quickly come to the p-type side of the junction. Once, the newly created free electrons come to the n-type side, cannot further cross the junction because of the barrier potential of the junction.
Similarly, the newly created holes once come to the p-type side cannot further cross the junction because of the same barrier potential of the junction. As the concentration of electrons becomes higher on one side, the p-n junction will behave like a small battery cell. A voltage is set up which is known as photovoltage. If we connect a small load across the junction, there will be a tiny current flowing through it. The IV characteristic of solar cells is given below:
Answer the following questions:
(a)
Is the principle of a solar cell the same as that of a photodiode?
(b)
What is the suitable band gap of the semiconductors used as solar cell materials?
- (a)0 to 0.5 eV
- (b)0.5 to 1 eV
- (c)1.1 to 2 eV
- (d)0 to 0.8 eV
(c)
What does $V_0$ represent in the characteristic curve?
(d)
Is $I_{max}$ independent of the intensity of incident radiation?
(e)
Why do holes in the depletion region quickly come to the p-side?
Answer
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From ISC 2025 Practice Physics, question 93.