SEMICONDUCTOR NON-TRADITIONAL ENERGY SOURCES |
In right figure the energy diagram of a solar cell used by the further consideration (solar radiation falls on right n-area). The value of a solar cell photocurrent can be, as a first approximation, submitted as the sum of three components: JL = Jp + Jn + Jdl, where Jp, Jn - photocurrents arising at absorption photons accordingly in p- and n- areas, Jdl - photocurrent created by carriers absorbed in a depleted layer of pn-junction. Taking into account, that practically all carriers of a charge generated in depleted layer create a photocurrent it is possible to write down:
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_{ wherе z = x - xp. It is necessary to pay attention, that factor of absorption depends on factor of photon absorption, which enters in the describing photocurrent second member of the equation, follow exponent law. It means, that the short-wave part of a spectrum of radiation, for which factor of absorption is great, will give the weak contribution to this current, because these photons generate carriers too close to the surface, where they recombine. The equation for a complete current in frontal n-area (see drawing in the beginning of this page) will be written down so: , where z = x - xp. The equation for photocurrent in n-region: , where = x'n - xn. IN-DEPTH STUDY }