Optoelectronics: Photodiodes, LEDs, and Solar Cells
1. In a photodiode, which of the following conditions must be satisfied for photon absorption to occur?
2. What is the main purpose of reverse biasing a photodiode?
3. In an LED, radiative recombination occurs when:
4. If the quantum efficiency η of a photodiode is 0.6, Popt = 2 mW, and photon energy hν = 3.2 × 10⁻¹⁹ J, calculate the photocurrent Iph. Use q = 1.6 × 10⁻¹⁹ C.
5. For an LED with internal quantum efficiency ηint = 0.7, Rrad = 7×10²³ s⁻¹, what is Rnonrad?
6. In a solar cell, if Voc = 0.6 V, Isc = 30 mA, FF = 0.8, and Pin = 50 mW, calculate efficiency η.
7. A silicon photodiode operates at λ = 900 nm. Find the minimum bandgap Eg required for photon absorption. (Use h = 6.626×10⁻³⁴ J·s, c = 3×10⁸ m/s, q = 1.6×10⁻¹⁹ C.)
8. A solar cell has Isc = 40 mA, Voc = 0.65 V, and FF = 0.75. If its efficiency η = 30%, calculate the input power Pin.
9. In a laser diode, what condition must be satisfied for stimulated emission to dominate?