LPE GROWTH AND CHARACTERIZATION OF INGAASP INP HETEROSTRUCTURES - IR LIGHT-EMITTING-DIODES AT 1.66 MU-M - APPLICATION TO THE REMOTE MONITORING OF METHANE GAS/

Highly effective IR light-emitting diodes operating at the wavelength 1.66 mu m and based on the buried heterostructure In0.88Ga0.12As0.26P0 .74/ In0.72Ga0.28As0.62P0.38/In0.53Ga0.47As/InP have been grown by liq uid-phase epitaxy (LPE) and characterized in detail by means of transm ission electron microscopy (TEM), high-resolution electron microscopy (HREM),electron diffraction (ED), X-ray diffraction (XRD), secondary-i on mass spectrometry (SIMS) and electroluminescence measurements. The InGaAsP epilayers are found to be well lattice matched and of good str uctural quality. A tentative explanation is presented for the spinodal decomposition observed in InGaAsP alloys. A new type of selective CK, gas sensor has been developed and fabricated an the basis of the IR l ight-emitting diode mentioned above. Especially designed for the remot e control of CH4 gas via fibre optics, an integrated optoelectronic re adout scheme has been developed and tested, It is shown that the propo sed type of sensor can be used for the quantitative remote control of CH4 gas concentration (0.2-100%) via a fibre glass line up to a distan ce of 2 x 1 km. (C) 1997 Elsevier Science S.A.