An optical technique for measuring surface recombination velocity

Recombination velocity of SiN<inf>x</inf>:H/silicon interfaces and the relationship of insulator charge.

“…The latter describes the electron-hole density after the initial distribution becomes "flat" throughout the volume because of diffusion. The diffusion profile flattens in a time of about 20 microseconds [5], which is much shorter than significant carrier loss from recombination. The initial injection level then is many times the background doping level.…”

Study of recombination in CdMgTe/CdTeSe heterostructures using photoluminescence intensity and lifetime measurements with confocal photoluminescence microscopy

“…This analysis assumes that the TRPL is monitored for a sufficiently long time that the carrier density is in the low injection regime and that the excess carriers have been able to diffuse until distributed uniformly in the volume. In this equilibrium limit, the lifetime is approximately given by [5] 1/τ = 1/τbulk + 2S/d (1) where τ = τeff is the measured TRPL lifetime and d is the absorber thickness. The intercept at high thickness then becomes an estimate of the material's internal bulk lifetime, τbulk >700 ns.…”

“…[4] Meanwhile, the decay rate in the short time limit is often used to characterize the surface recombination velocity (S). [5] Unfortunately, the decay behavior in the short time limit is typically controlled by a combination of diffusion and surface recombination, [6] and S may not behave as a single physical parameter, but instead strongly depend on excitation. [7] Therefore, it can be difficult to determine when recombination rates are dominated by surfaces and interfaces [8] as opposed to bulk defects such as dislocations or twins, which are known to be centers of non-radiative recombination as well.…”

Spectral dependence of carrier lifetimes in silicon for photovoltaic applications

“…However, access to a large set of wafers for such types of analyses may not always be possible or convenient. In addition to the steady state or the QSS photoconductance approach, optical transient decay experiments 5,16–18,23–25 have also been used, mostly consisting of pump-probe or two-beam measurement techniques. Surface vs bulk effects can be determined by examining the temporal behavior of the decaying probe signal.…”

“…Specifically, our work was focused on the QSSPC method, which is a very well-established technique and made it possible to take advantage of the steady-state equations of charge carrier transport developed in reference 10. The plurality of the spectral dependence studies in the literature has been achieved with transient methods employing tunable fast laser pulses and time resolved detection 4,5,16–18,20 . The few reports of spectral-dependent effects to-date, utilizing the QSSPC method and governing equations, have been mostly focused on the use of bandpass filters to select a given spectrum from a broad-spectrum flash source 11,12,14,15 .…”