A `p-n` photodiode is made of a material with a band gap of `2.0 eV`. The minimum frequency of the radiation that can be absorbed by the material is nearly

Options

A. `10xx10^14` Hz
B. `20xx10^13` Hz
C. `5xx10^13` Hz
D. `5xx10^14` Hz

Answer

D

Explanation

Band gap `E_g=hv=2eV=2xx1.6xx10^(-19)` J
`therefore ` The minimum frequency is given by `hv_"min"` = 2 eV
`therefore v_"min" = (2xx1.6xx10^(-19)) /h =(3.2xx10^(-19))/(6.6xx10^(-34))`
`=0.5xx10^(+15) = 5xx10^(+14) ` Hz