Learning Forum

[Mariah Ha]

Hi all, 

I am confused about the value of surface recombination velocity that we should put as a boundary condition between silicon and glass (SiO2). I went through some Lumerical charge examples such as the Vertical photodetector, and solar silicon pillar, avalanche photodetector etc... The value used for surface recombination velocity at Si/SiO2 interface is sometimes 1000 cm/s , and sometimes 100 cm/s. In all the examples, that value is big and not close to 0  . Some websites mention that it should be small close to 0, here for example at the bottom of the website (Electrical properties of Silicon (Si) (ioffe.ru)) .

Thank you .

[Guilin Sun]

Surface recombination can be defined as the product of surface recombination velocity and the difference in minority carrier concentrations between thermal equilibrium and at the surface, and surface recombination velocity depends on some intrinsic material parameters, such as the minority carrier diffusion length (Fitzgerald and Grove, 1968).

In addiiton, the surface recombination velocity is also dependent on the surface roughness, contamination and defects.

That said, if you have a perfect, ideal semiconductor surface, this velocity is very small, if not zero. In most cases, such recombination only has effect of about a few percent at most. Other parameters may have larger effect. My personal suggestion is, simply use a value and try the result. You can also compare results with different values.

With the above information, together with what you can find online search, probably other questions are not questions.

 

 

[Mariah Ha]

Thank you for the detailed answer.