A semiconductor is irradiated with light such that carriers

A semiconductor is irradiated with light such that carriers are uniformly generated throughout its volume. The semiconductor is n-type with N_D = 10¹⁹ per cm³. If the excess electron concentration in the steady state is ∆n = 10¹⁵ per cm³ and τP = 10 µ sec. [minority carrier liftime] the generation rate due to irradiation—

1. Is 10²⁰ e^-h pairs/cm³/s
2. Is 10²⁴ e^-h pairs/cm³/s
3. Is 10¹⁰ e^-hpairs/cm³/s
4. Cannot be detemined as the given data is insufficient

We know that

Rate of generation of minority carriers		100 x 5	dp
		dt

=	excess hole concentration
	minority carrier life time

but at equilibrium (steady state)
∆P = ∆n

		dp	=	∆n	=	10¹⁵
		dt		τ_p		10 × 10^–6

= 10²⁰ e-h pairs/cm³/sec.
Hence alternative (A) is the correct answer.