Highly Strained Mid-Infrared Type-I Diode Lasers on GaSb

Abstract

We describe how growth at low temperatures can enable increased active layer strain in GaSb-based type-I quantum-well diode lasers, with emphasis on extending the emission wavelength. Critical thickness and roughening limitations typically restrict the number of quantum wells that can be grown at a given wavelength, limiting device performance through gain saturation and related parasitic processes. Using growth at a reduced substrate temperature of 350 °°°°C, compressive strains of up to 2.8% have been incorporated into GaInAsSb quantum wells with GaSb barriers; these structures exhibited peak room-temperature photoluminescence out to 3.96 μm. Using this growth method, low-threshold ridge waveguide lasers operating at 20 °C and emitting at 3.4 μm in pulsed mode were demonstrated using 2.45% compressively strained GaInAsSb/GaSb quantum wells. These devices exhibited a characteristic temperature of threshold current of 50 K, one of the highest values reported for type-I quantum-well laser diodes operating in this wavelength range. This temperature stability is attributable to the increased valence band offset afforded by the high strain values, due to the simultaneously high quantum well indium and antimony mole fractions. Exploratory experiments using bismuth both as a surfactant during quantum well growth, as well as in dilute amounts incorporated into the crystal were also studied. Both methods appear promising avenues to surmount current strain-related limitations to laser performance and emission wavelength.

Next-generation mid-infrared sources

“…However, increasing the In fraction in the QW also decreases the valence band offset between the well and barrier [82]. As a result, the InGaAsSb/AlGaAsSb material system suffers from poor hole confinement in the QWs with increasing In concentration in the QWs, which is an effect that has damaging repercussions for laser performance [83].…”

Wavelength Dependence of Efficiency Limiting Mechanisms in Type-I Mid-Infrared GaInAsSb/GaSb Lasers

“…However, an exponential increase in the threshold current density is typically observed with increasing temperature [4]. The degradation in performance is generally attributed to the aggregate effect of non-radiative recombination, carrier leakage and optical loss processes such as IVBA.…”

“…Developments in material quality and structural design over several decades have established the type-I active region as the most competitive laser geometry in the 2-3 µm spectral range [4]. High performance lasers based on the GaInAsSb/GaSb material system have reported Watt-level output powers up to 2.5 μm [5] and hundreds of milli-Watts at wavelengths past 3μm [6].…”

Growth and properties of rare-earth arsenide InGaAs nanocomposites for terahertz generation

“…Bismuth, on the other hand, is a much larger atom with a slightly lower electronegativity and incorporates at substrate temperatures much lower than the standard growth conditions. 52,53 Bismuth, much like antimony, has also been demonstrated as a surfactant to improve Ge/Si interfaces, 54,55 improve the structural and optical quality of highly strained In x Ga 1Àx As/GaAs 56 and In x Ga 1Àx As y Sb 1Ày 57 heterostructures, increase the incorporation of nitrogen in dilute GaNAs and GaInNAs layers on GaAs, 52,58 and improve the quality of lattice-matched layers of InGaAs on InP. 59 Despite the range of improved materials through surfactant-mediated growth, there has been no report exploring its application to the growth of RE-As nanocomposites.…”