Strain dependence of Auger recombination in 3 μm GaInAsSb/GaSb type-I active regions

Abstract

We differentiate the effect of strain induced by lattice-mismatched growth from strain induced by mechanical deformation on cubic nonradiative Auger recombination in narrow-gap GaInAsSb/GaSb quantum well (QW) heterostructures. The typical reduction in the Auger coefficient observed with lattice-mismatched growth appears to be due to the concomitant compositional change rather than the addition of strain, with implications for mid-IR semiconductor laser design. We induced a range of internal compressive strain in five samples from −0.90% to −2.07% by varying the composition during the growth and mechanically induced a similar range of internal strain in analogous quantum well membrane samples. We performed time-resolved photoluminescence and differential reflectivity measurements to extract the carrier recombination dynamics, taken at 300 K with carrier densities from 2.7×1018 cm−3 to 1.4×1019 cm−3. We observed no change with strain in the cubic Auger coefficient of samples that were strained mechanically, but we did observe a trend with strain in samples that were strained by the QW alloy composition. Measured Auger coefficients ranged from 3.0×10−29 cm6 s−1 to 3.0×10−28 cm6 s−1.

Comparison of Auger Coefficients in Type I and Type II Quantum Well Midwave Infrared Lasers

“…Figure 4 expands that analysis by including the converted 3D results for T1QWs (red points) [16], [17], [19], [29]- [30], [33]- [40]. The open red points are extracted from threshold data acquired at University of Surrey using hydrostatic pressure to vary the bandgap, and hence the emission wavelength, of a given device [19].…”

“…This supposition was supported by the measurement of a relatively high Auger coefficient for a type-I InAs0.85Sb0.15-In0.87Al0.13As0.91Sb0.09 multiple quantum well (MQW) [28]. However, several groups subsequently showed that mid-IR InGa(As)Sb T1QWs, with GaSb or AlGa(In)AsSb barriers and grown on GaSb with much greater strain, can also display significant suppression of the Auger decay rate [13], [16], [17], [19]. This is not really surprising since, as in T2QWs, compressive strain splits the valence band degeneracy at k = 0 and induces a much lighter in-plane heavy hole mass near the zone center.…”

“…Defying earlier expectations, this and the strong Auger suppression associated with the T2QW band structure allowed mid-IR T2QW lasers, in particular the interband cascade laser (ICL) [26], [27], to display low thresholds and high output powers (up to 500 mW) when operated in continuous wave (cw) mode at room temperature. 17 Following the prediction and experimental confirmation of substantial Auger suppression in T2QWs compared to bulk materials, it was generally taken for granted that they also have smaller Auger coefficients than mid-IR T1QWs with the same bandgaps. This supposition was supported by the measurement of a relatively high Auger coefficient for a type-I InAs0.85Sb0.15-In0.87Al0.13As0.91Sb0.09 multiple quantum well (MQW) [28].…”

“…It should also be mentioned that since most of the T1QW lasers have 2-3 wells per stage and the type-II ICLs have 3-10 stages that must be biased in series, the relative threshold input power density (jth × Vth) may look quite different from the comparison in this figure, as will be discussed further below. wavelength for T1 InGaAsSb QW and T2 interband cascade lasers 17 operating at room temperature. The T1 lasers were reported by U. Surrey [16], [19], [34] (all open red points), MIT Lincoln Lab [28] (filled upside-down triangles), SUNY diodes [29], [35]- [39] (filled triangles), SUNY T1 ICLs (filled squares) [30], and Brolis [40] (filled diamonds).…”

“…Although this procedure extracts a 2D Auger coefficient from the QW laser threshold, and all state-of-the-art III-V mid-IR lasers employ T1 or T2 QWs instead of bulk materials, it is nonetheless convenient to relate the 2D values to a 3D representation so comparison may also be made to bulk mid-IR materials [22]. Moreover, most previous investigations of Auger recombination in QWs have reported 3D rather than 2D Auger coefficients (e.g., [17], [41][42][43]), so a conversion is needed, at the very least, to place the earlier studies in context. We accomplish this transformation by calculating a normalization length corresponding to the quantum-confined carrier's spatial extent along the growth axis, which may be derived using the wavefunctions ψe and ψhh for the relevant electron and hole subbands [15].…”