Engineering
Engineering, 19.11.2019 06:31, mxlx27

An led, light emitting diode, is basically just a pn junction emitting light, due to photon generation from e-h recombination, when forward biased. ideally we want current injection to be of only one type of carrier. given a gaas pn junction at t = 300k with: area = 0.7 mm2, na = 2e16 cm-3, nd = 3e17 cm-3, τn = 1e-8 sec, τp = 1e-7 sec, dn = 30 cm2/s, dp= 15 cm2/s.(a) show that the minority hole current can be ignored compared to the minority electron current.(b) when forward biased at v,-1 v, what is the photon generation rate (# photons / sec)? what is the light emission power (power-energy /time)? assume that all electrons injected into the p region recombine with holes to generate photons, i. e. quantum efficiency-1.

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