Consider a silicon sample at T = 300 K, with a uniform donor density N_d = 5 × 10¹⁶ cm^-3 illuminated uniformly such that the optical generation rate is G_opt = 1.5 × 10²⁰ cm^-3 s^-1 throughout the sample. The incident radiation is turned off at t = 0. Assume low-level injection to be valid and ignore surface effects. The carrier lifetimes are τ_p0 = 0.1 µs and τ_n0 = 0.5 µs.
The hole concentration at t = 0 and the hole concentration at t = 0.3 µs, respectively, are

A. 1.5 × 10¹³ cm^-3 and 7.47 × 10¹¹ cm^-3

B. 1.5 × 10¹³ cm^-3 and 8.23 × 10¹¹ cm^-3

C. 7.5 × 10¹³ cm^-3 and 3.73 × 10¹¹ cm^-3

D. 7.5 × 10¹³ cm^-3 and 4.12 × 10¹¹ cm^-3

Answer: Option A