Physics - Semiconductors Question with Solution | TestHub

The maximum wavelength of radiation that can be detected corresponds to the minimum energy required to excite an electron, which is the band gap energy $E_g$. The relationship between energy and wavelength is $E_g=\frac{hc}{{\lambda }_{max}}$.${\lambda }_{max}=\frac{hc}{E_g}=\frac{6.626\times 10^{-34}\text{ Jcdots}\times 3\times 10^8\text{ m/s}}{2.0\text{ eV}\times 1.6\times 10^{-19}\text{ J/eV}}$ ${\lambda }_{max}=\frac{19.878\times 10^{-26}}{3.2\times 10^{-19}}\text{ m}=6.211875\times 10^{-7}\text{ m}=621.1875\text{ nm}$. Rounding to the nearest integer, the maximum wavelength is 621 nm.