Q

Quantum efficiency

This is the number of electrons or holes that can be extracted as photocurrent divided by the number of incident photons. It is commonly expressed in percent (%). The quantum efficiency QE and photosensitivity S (unit: A/W) have the following relationship at a given wavelength (unit: nm).$$QE=\biggl( \frac{S \cdot 1240}{\lambda}\biggr)\cdot 100\ [％]$$ S : Photosensitivity (A/W)
λ : Wavelength (nm)

Quenching

Quenching means extinction or rapid cooling. In an APD operated in Geiger mode, quenching is a technique to stop Geiger discharge by reducing the reverse voltage below the breakdown voltage.