Recombination-generation lifetime electrons

Multiphonon generation is the inverse of multiphonon recombination. Multiphonon generation is a thermally activated process. Electrons are diermally excited from G-R centers into the conduction band and holes are similarly thermally excited from G-R centers into the valence band. The key feature of SRH generation is thermal excitation. A thermally activated process is very dependent on the temperature and on the activation energy. We define a generation lifetime as [60]... 

Let us now calculate radiative lifetime including reabsorption. Radiative recombination rate per unit frequency for the case of reabsorption can be represented as Eq. (1.25) multiplied by Pe, probability for a photon to leave the sample after being generated in electron-hole recombination... 

The equihbtium lever relation, np = can be regarded from a chemical kinetics perspective as the result of a balance between the generation and recombination of electrons and holes (21). In extrinsic semiconductors recombination is assisted by chemical defects, such as transition metals, which introduce new energy levels in the energy gap. The recombination rate in extrinsic semiconductors is limited by the lifetime of minority carriers which, according to the equihbtium lever relation, have much lower concentrations than majority carriers. Thus, for a -type semiconductor where electrons are the minority carrier, the recombination rate is /S n/z. An = n — is the increase of the electron concentration over its value in thermal equihbtium, and... 

The mobile charge carrier species may either recombine or reach the semiconductor surface, where they can be trapped by the surface adsorbates or other sites. The lifetime of electron-hole (e /h+) pairs that are generated is important in determining the reaction yield. The holes are mainly trapped by water molecules or hydroxyl ions, giving rise to very reactive hydroxyl radicals ... 

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