Question

A p-n junction diode is made up of a material which has energy gap of $3.0\text{eV}$. The maximum wavelength of radiation that can be absorbed by the material is nearly equal to

• A. $6216A^{\circ }$
• B. $5426A^{\circ }$
• C. $4140A^{\circ }$
• D. $3146A^{\circ }$

Answer 1

The correct option is C $4140A^{\circ }$

Given energy gap is $3eV$
$h\nu =3\text{eV}$
$\frac{hc}{\lambda }=3\times 1.6\times {10}^{-19}$
$(hc\simeq 20\times {10}^{-26})$
$\Rightarrow \lambda =\frac{20\times {10}^{-26}}{4.8\times {10}^{-19}}$
$\Rightarrow \lambda =4140A^{\circ }$