In a (p )-type semiconductor the donor level is at (50 meV ) above the valence band. To produce one electron, the maximum wavelength of light photon required is (Planck's constant, (h=6.6 10⁻³⁴ Js ) and speed of light in vacuum, (c=3 10^8 ~ms ⁻¹ ) )

Step-by-step solution

Given, (p )-type semiconductor donor energy level, (E=50 meV =50 10⁻³ 1.6 10⁻¹⁹ ~V ) Planck's constant, (h=6.6 10⁻³⁴ Js ) speed of light in vacuum, (c=3 10^8 ~m / s ) Now, for the maximum wavelength of light photon's required ((p) ). According to the Planck's quantum theory, ( E=h v E= h c [ v= c ] ) Putting the given values, we get (50 10⁻³ 1.6 10⁻¹⁹= 6.6 10⁻³⁴ 3 10^8 ) ( aligned & = 6.6 10⁻³⁴ 3 10^8 50 10⁻³ 1.6 10⁻¹⁹ & = 6.6 3 10⁻³⁴ 10^8 5 16 10⁻²² = 6.6 3 10⁻⁴ 5 16 & =2.475 10⁻⁵ ~m or & =24.75 10⁻⁶=24.75 m align