Recombination Handout - University of California, Berkeley...

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University of California, Berkeley EE230 - Solid State Electronics Prof. J. Bokor Recombination Handout.fm Recombination Processes (reading in supplementary references: Singh, Pankove) Radiative recombination Radiative recombination is the reverse of absorption. If excess carriers are present, the sys- tem is not in equilibrium. This can lead to the emission of photons which is sometimes referred to as luminescence. Luminescence is sometimes specified based on the method of excitation as follows: We can calculate the emission rate and spectrum from absorption rate and spectrum. The method is similar to the Einstein A & B coefficient analysis for atoms. We put the system in thermal equilibrium. Then emission rate = absorption rate. The ther- modynamic principle of detailed balance holds that the rates must balance for each fre- quency ν . We also can relate the absorption probability to the absorption coefficient: Excitation Process Emission Process Current Injection Electroluminescence Optical Excitation Photoluminescence Electron Beam Excitation Cathodoluminescence Ultrasonic Acoustic Excitation Sonoluminescence R ν () d ν P ν ρν d ν = emission rate per unit volume probability per unit time of absorbing photon ν density of pho- tons of freq ν
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- 158 - University of California, Berkeley EE230 - Solid State Electronics Prof. J. Bokor where n is the index of refraction. In thermal equilibrium, the photon field is described by the Planck distribution: Plugging these in, we find:
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This note was uploaded on 08/01/2008 for the course EE 230 taught by Professor Bokor during the Spring '08 term at University of California, Berkeley.

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Recombination Handout - University of California, Berkeley...

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