Gadolinium-doped InGaAsSb solid solutions on an InAs substrate for light-emitting diodes operating in the spectral interval λ=3–5 µm

The influence of a gadolinium impurity on the electrical and luminescence characteristics of epitaxial structures made from narrow-gap n-InGaAsSb solid solutions grown by liquid-phase epitaxy on InAs substrates is investigated. The addition of gadolinium to the flux solution in the interval of concentrations 0<XGdl⩽0.14 at. % has the effect of lowering the density of electrons in the InGaAsSb layers from (3–6)×1016 cm−3 to (7–8)×1015 cm−3 and increasing the carrier mobility from 32 000 cm2/(V·s) to 61 500 cm2/(V·s) (T=77 K). Also observed are a decrease in the half-width of the photoluminescence spectra from 25 meV to 12 meV and as much as a tenfold increase in their intensity (T=77 K). The electroluminescence intensity of LEDs fabricated from gadolinium-doped n-InGaAsSb/p-InAs epitaxial structures (T=300 K) increases approximately a factor of 2 relative to the undoped samples.