MHTCET 17 Apr 2026 Shift 2 Paper

Concept:Doping germanium with a group 13 element forms a p-type semiconductor, while doping with a group 15 element forms an n-type semiconductor.Explanation:Germanium ($\mathrm{Ge}$) has $Z = 32$, so it belongs to group 14 and has 4 valence electrons.Indium ($\mathrm{In}$) has $Z = 49$.It belongs to group 13 and has 3 valence electrons.Doping $\mathrm{Ge}$ with $\mathrm{In}$ creates acceptor atoms, producing holes as majority charge carriers.Therefore, semiconductor X is p-type.Arsenic ($\mathrm{As}$) has $Z = 33$.It belongs to group 15 and has 5 valence electrons.Doping $\mathrm{Ge}$ with $\mathrm{As}$ creates donor atoms, providing excess electrons as majority charge carriers.Therefore, semiconductor Y is n-type.In the given circuit, the p-side X is connected to the negative terminal of the battery.The n-side Y is connected to the positive terminal of the battery.For a p-n junction, forward bias occurs when the p-side is positive and the n-side is negative.Reverse bias occurs when the p-side is negative and the n-side is positive.Since the p-side is negative and the n-side is positive, the junction is reverse biased.Answer:Option B: $\mathrm{X}$ is p-type, $\mathrm{Y}$ is n-type, and the junction is reverse biased.