Cpd. semiconductor substrate for improved light emitting diodes - has epitaxial gallium-arsenide-phosphide layer on top or layer with improved lattice matching combining gradual and stepped compsn. changes

摘要

Epitaxial substrate comprises GaAs or PaP single crystalline wafer on which an epitaxial deposited GaAs1-xPx layer with a fixed compsn. is grown. The substrate also contains an intermediate layer of which part(s) micron(s) thick, has a constant compsn. and parts have a graded compsn. with a rate of change (delta(x)) of the value of x given by : delta(x) is at least 0.02 and not greater than 0.08. The layers with different compsn., used in the intermediate layer, are pref. deposited in conditions of changing material supply rate and temp. the layer(s) with constant compsn. in the intermediatee layer are deposited pref. at constant temp. and material supply. The first layer of the intermediate layer is pref. deposited at a temp. of 970-890 deg.C and the last layer pref. at 910-800 deg.C. USE/ADVANTAGE - Layer gives better matching of the lattices of the layers of different compsns. than currently used layers with continuously varying compsn. This is shown by a lower incidence of lattice faults and a higher light emission for light emitting diodes made using the substrates.