Optical Measurement Techniques of Recombination Lifetime Based on the Free Carriers Absorption Effect
Figure 2
(a) Intrinsic or band-to-band absorption occurs when the energy of the absorbed photon is greater than the material band-gap. (b) Extrinsic or impurity level to band absorption occurs in extrinsic materials when the photon energy is greater than the impurities energy but smaller than the energy band-gap. In the figure the process is sketched in the case of a p-type semiconductors. (c) Intraband or free carriers absorption can occur when the photon energy is smaller than the energy band-gap.
