Topic: Optoelectronic Devices
The electrical conductivity of a semiconductor increases when a radiation of wavelength shorter than 1000 nm is incident on it. The band gap of the semiconductor is:
- A. 2.4 eV
- B. 1.2 eV
- C. 3.4 eV
- D. 4.0 eV
Answer: B. 1.2 eV
Explanation: Wavelength λ = 1000 nm = 1 μm. Bandgap energy E_g ≈ 1.24 / λ(μm) eV = 1.24 / 1 ≈ 1.2 eV.