Carrier diffusion and recombination in highly excited InGaN/GaN heterostructures

Abstract

Time‐resolved four‐wave mixing and photoluminescence techniques have been combined for studies of MOCVD‐grown InxGa1–xN/GaN/sapphire heterostructures with different indium content (0.08 < x < 0.15). In‐plane diffusion and recombination of spatially‐modulated carriers, confined in the front layer of 50‐nm‐thick InGaN, were monitored by a probe beam diffraction and provided an average value of a bipolar diffusion coefficient D ≈ 1–1.5 cm2/s and its dependence on the In content. A complete saturation of four‐wave mixing (FWM) efficiency vs excitation energy was found prominent in a layer with 10% of In. The latter effect of saturation correlated well with the dependence of quantum efficiency of stimulated emission on In content in heterostructures. Short decay times of stimulated emission (∼10 ps) measured by time‐resolved PL in highly excited structure allowed us to attribute the FWM saturation effect to the threshold of stimulated recombination. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High-excitation luminescence properties of m-plane GaN grown on LiAlO2 substrates

“…After exceeding a certain generation level, the average carrier concentration does not increase with higher excitation. This peculiarity has been previously observed in InGaN [20] and GaN epitaxial layers [21], and correlation with time-resolved PL studies showed evidence for the onset of stimulated carrier recombination. In the given study, we observe a rather strong correlation between the SE threshold values determined by TG and PL backscattering techniques for m-plane and c-plane GaN layers.…”

Characterization of Optical and Photoelectrical Properties of ZnO Crystals

“…2 in Ref. [5]). Time-resolved kinetics of TG decay directly provided carrier lifetimes in the undoped and doped PLD ZnO layers (Fig.…”

“…To record the grating, an interference pattern of two τ = 7 ps duration laser beams with wavelength λ = 351 nm (hν = 3.53 eV) was used to create a modulated free-carriers spatial distribution (i.e. a transient free-carrier diffraction grating [5]). The grating decay was probed by a weakly absorbed beam at λ = 1064 nm which propagated through the sample and created a diffracted pattern behind the sample.…”

Direct study of nonlinear carrier recombination in InGaN quantum well structures

“…The further decrease of carrier lifetime at higher excitations was due to the onset of ultrafast stimulated recombination (see inset in Fig. 2; this effect was also observed in InGaN/GaN heterostructures by using TRPL and LITG techniques [12]). The SE suppresses the further increase of carrier density, because stimulated emission extremely rapidly exhausts an inverse population and reduces carrier density value, which further decays by bimolecular recombination.…”