Concepts Of Physics MCQ Edition [Volume 2]PhysicsSemiconductors and Semiconductor Devices
Determine the maximum wavelength of electromagnetic radiation capable of creating a hole-electron pair in germanium. The band gap of germanium is 0.65 eV .
Options
- A1.9 10⁻⁵ m
- B1.9 10⁻⁶ m
- C3.8 10⁻⁶ m
- D1.9 10⁻⁷ m
Correct answer
B. 1.9 10⁻⁶ m
Step-by-step solution
The energy required to create a hole-electron pair is equal to the band gap energy E_g . The maximum wavelength _ max of the electromagnetic radiation is given by: _ max = hc E_g Converting the band gap energy into Joules: E_g = 0.65 eV = 0.65 1.6 10⁻¹⁹ J = 1.04 10⁻¹⁹ J Substituting the values of Planck's constant h and speed of light c : _ max = 6.63 10⁻³⁴ 3 10^8 1.04 10⁻¹⁹ m _ max = 19.89 10⁻²⁶ 1.04 10⁻¹⁹ m _ max 19.1 10⁻⁷ m _ max 1.9 10⁻⁶ m