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davelandsman

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1.Construct a semilogarithmic plot for Si doped with 2X10^15 donors/cm3 and having 4x10^14 EHP/cm^3 created uniformly at t=0. assume that tn = tp = 5us.

2.calcualte the recombination coefficient alphar for the low-level ecitation described in problem 1. assume that this value of alphar applied when the GaAs sample isuniformly exposed to a steady state optical generation rate gop = 10^19 EHP/cm^3-s. find the stead state excess carrier concentration.

3. For a 2cm long doped Si bar with a cross sectional area = 0.05 cm^2. what is the current ifwe apply 10V across it? if we generate 10^20 electron-hole pairs per second per cm^3 uniformaly in the bar and the lifetime tn = tp = 10^-4s, what is the new current? assume the low-level alphar doesn't change for high-level injection. if the voltage is then increased to 100,000V, what is the new current? Assume up=500cm^2/Vs, but you must choose the appropriate value for electrons.

4. A 100 mW laser beam with wavelength = 6328 is focused onto a GaAs sample 100um thick. the absorption coefficient at this ewavelength is 2X10^4 cm^-1. find the number of photons emitted per second by radiative recombination in the GaAs, assuming perfect quantum efficiency. what power is delivered to the sample as heat?

Thank you.