All the books I read talk about carrier recombination lifetime when the semiconductor material is pushed out of equilibrium. But let's say the material is in equilibrium ( where generation and recombination happen at the same rate) and the carrier is only generated thermally and the only recombination method is direct band to band. What would be the carrier recombination lifetime in this case? Can this lifetime be calculated or measured?
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
2
The (net) recombination lifetime is usually defined as the characteristic time for a non-equilibrium excess carrier distribution to return to equilibrium. In equilibrium such a lifetime is not applicable.
PS: In case you are looking for the time constant in thermal equilibrium of generation and recombination for a minority electron/hole to recombine with a majority hole/electron, it can easily be shown that this is the same as the usual non-equilibrium low-injection minority carrier lifetime.
-
$\begingroup$ Let's say that an intrinsic material is in thermal equilibrium with generation rate (g) equals recombination rate (R) assuming only band-to-band recombination/generation. Wouldn't the lifetime for both holes and electrons be simply$\tau=\frac{n_{0}}{g}=\frac{p_0}{R}$ where p0 and n0 are the equilibrium carrier concentrations? $\endgroup$– AbeCommented Apr 6 at 5:03
-
1$\begingroup$ @Abe Yes, in the intrinsic thermal equilibrium case, with intrinsic equal electron and hole concentrations, this should be the characteristic mean time ("lifetime") it would take an electron or a hole to recombine. The inverse of this time is the probability per unit time for an electron or hole to recombine. $\endgroup$ Commented Apr 6 at 15:24