Hey everyone, I have a question relating to surface recombination velocity. I assume that the interface of GaAs/Si would produce a lower quality than between GaAs/GaAlAs due to the fact that my notes state that GaAs/GaAlAs is most common in double heterostructure for lasers. I would like to know why this is the case (if my prediction is correct). Is it just a geological problem such as the interface between GaAs/Si has more defects and thus a higher non-radiative recombination rate?

I was thinking along the lines of the difference in band gaps: GaAs has an energy gap of around 1.42 eV, AlGaAs 1.79 eV and Si 1.1 eV. By looking at the differences between the two, GaAs/GaAlAs would have a band gap of 0.37 eV and GaAs/Si 0.32 eV. I don't think this will help with my above question but was wondering what this could tell me about the device.

Thanks!

 

Hi. It is to do with both the lattice defects and the difference in bandgap energy because for the non-radiative recombination both are factors affecting the recombination rate and thus the threshold current of a laser.

http://lyle.smu.edu/ee/smuphotonics/Gain/CoursePresentationFall03/Aug29_ywan.pdf