- Quantum efficiency:-
- Quantum efficiency is defined as rate of generation of electron hole-pairs for per incident rate of photon energy.
- It depends on the absorption co-efficient and the wavelength of light.
- η<1 η=re/rp (electron/sec)/(photons/sec)
Ip = ne∂q/∂t = q ∂ne/∂t = qre ——————— 1.
Po = np ∂E/∂T = E ∂ne/∂t = Erp ——————–2.
From equation 1&2,
η = (Ip/q)/(Po/E)
η=Iphc/Poqλ
2. Responsivity:-
- Responsivity tells you about the performance of photo detector and provides the conversion efficiency of photo detector.
- It is defined as the ratio of photo current generated per unit optical power.
- It defines the transfer characterstics of a photo detector for a pertricular wavelength.
R= Ip/Po η=Iphc/Poqλ
η = R hc/q λ
Electronics Tutorial 