What is the thickness of the n - type semiconductor of p - n junction diode used for photovoltaic effect to generate solar energy?

The correct answer is option 3):(Less than one micrometre)

Concept:

• A pn junction separates the electron and hole carriers in a solar cell to create a voltage and useful work. 
• When light reaches the p-n junction, the light photons enter the junction, through a very thin p-type layer.
• The light energy, in the form of photons, supplies sufficient energy to the p-n junction to create a number of electron-hole pairs.
• The incident light breaks the thermal equilibrium condition of the junction. The free electrons in the depletion region can quickly come to the n-type side of the junction.
• In a practical solar cell, the top N layer is very thin and heavily doped; whereas the P layer is thick and lightly doped. This is to increase the performance of the cell. 
• The thickness of the n - type semiconductor of p - n junction diode used for photovoltaic effect to generate solar energy is Less than one micrometre