Comparison of surface and bulk contributions to non-radiative currents in InGaAs/AlGaAs laser diodes

Abstract

We present novel investigations of surface and bulk contributions to the non-radiative recombination in InGaAs/AlGaAs (λ = 0.98 µm) RW laser diodes. These enable us to explain earlier experiments, in which we extracted the non-radiative and the radiative current components from the power-voltage-current (P-V-I ) characteristics measured well below the threshold. From these experiments, the non-radiative current component was identified as primarily related to surface recombination, which increased during facet degradation, and could be decreased by a sulfur treatment. In this paper, we use these experimental results to estimate the drop of the surface recombination velocity after the sulfur treatment and to give an upper bound for the bulk carrier lifetimes. This is done by simulations of the V-I characteristics assuming that all non-radiative recombination takes place either at the surface or in the bulk.

Low-threshold surface-passivated photonic crystal nanocavity laser

“…Our observation of a four-fold lowering in S with surface passivation is similar to other reports with (NH 4 )S [12]. However, better passivation results could probably be achieved with (NH 4 )S x , x > 1, for which up to 50× improvement was reported [9].…”

“…We then find that S ≈ 1.7 · 10 5 cm/s (4.0 · 10 4 cm/s) for the original (passivated) structure. This value for the surface recombination velocity is somewhat lower than previous room-temperature measurements on similar InGaAs/GaAs structures by [9,10], which put it at between ∼ 1 · 10 5 and 5 · 10 6 cm/s. This is expected, since S ∝ v th ≈ 3kT /m * , the thermal velocity, which is ∼ 6× smaller at 10K [11].…”

“…In this regime, reducing the NR surface recombination rate lowers the lasing threshold as much as lowering the cavity loss rate 1/τ p would, but has the advantage of not slowing lasing modulation rate. Using a carrier diffusion model, we comparing this to literature, we believe that our results could be improved by applying better surface passivation techniques [9,15]. The increased efficiency achieved in our lasers alleviates heating problems, which opens the door to room-temperature and CW operation [2] and brings PC lasers closer to practical applications.…”

Record performance of electrical injection sub-wavelength metallic-cavity semiconductor lasers at room temperature

“…A surface recombination velocity (SRV) of 5 × 10 4 cm/s is obtained through RE fitting. This value is lower than typical SRV of InGaAs structures produced by dry etching processes which is 1~2 × 10 5 cm/s [34,35], and approaches the lowest value reported to our knowledge [36]. In summary, we demonstrated record performance of a RT CW sub-wavelength metalliccavity semiconductor laser, comparable to conventional semiconductor lasers, thus achieving a long sought goal in such lasers.…”

“…In such a sub-wavelength device, we estimate the surface recombination lifetime is on the order of nanoseconds. Typical bulk SRH recombination lifetime in metal organic chemical vapor deposition (MOCVD) grown high quality intrinsic III-V semiconductors is hundreds of nanoseconds [34], so SRH process is negligible compared to surface recombination and therefore ignored in our rate equation analysis. A surface recombination velocity (SRV) of 5 × 10 4 cm/s is obtained through RE fitting.…”