Gadolinium-doped InGaAsSb solid solutions on an InAs substrate for light-emitting diodes operating in the spectral interval lambda=3-5 mu m

The influence of a gadolinium impurity on the electrical and luminescence c haracteristics of epitaxial structures made from narrow-gap n-InGaAsSb soli d solutions grown by liquid-phase epitaxy on InAs substrates is investigate d. The addition of gadolinium to the flux solution in the interval of conce ntrations 0 < X(Gd)(l)less than or equal to 0.14 at. % has the effect of lo wering the density of electrons in the InGaAsSb layers from (3-6)x10(16) cm (-3) to (7-8)x10(15) cm(-3) and increasing the carrier mobility from 32 000 cm(2)/(V . s) to 61 500 cm(2)/(V . s) (T=77 K). Also observed are a decrea se 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 electro luminescence 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. (C) 1999 American Institute of Physics. [ S1063-7826(99)02608-3].