Determine intrinsic region width for a photodiode having drift time of 4×10 -10 s and electron velocity of 2×10 -10 ms -1 .

Optoelectronics and Optical Communication 

Determine intrinsic region width for a photodiode having drift time of 4×10 -10 s and electron velocity of 2×10 -10 ms -1 .

a) 3×10 -5 M 
b) 8×10 -5 M 
c) 5×10 -5 M 
d) 7×10 -5 M

Answer : - 8×10 -5 M

The drift time is given by 
t drift = w/v d 
4×10 -10 = w/2×10 5 
= 4×10 -10 ×2×10 5 
= 8×10 -5 m.