A p-Si photoconductor is to detect optical pulses having the waveform shown belo
ID: 1604425 • Letter: A
Question
A p-Si photoconductor is to detect optical pulses having the waveform shown below. Each pulse generates electron-hole pairs (ehp). When the pulse terminates, the ehp recombine according to the relation delta n_p (t) = delta n_p(0)exp(-t/tau_SRH) where t = 0 refers to the time when the light pulse is turned off. must have decreased to 0.01 delta n_p(0) before the next pulse is applied for proper photoconductor operation. For sigma_n = 10^-16 cm^2 and v_th = 10^7 cm/s, determine N_T for this to happen.Explanation / Answer
Delta np/np(0) = exp(-t/Tau)
.01 = exp (-t/Tau)
For t=100ns,
Tau = 46ns
----------------------------------