| abstract |
A semiconductor substrate ( 1 ) of GaAs with a semiconductor layer sequence ( 2 ) applied on top. The semiconductor layer sequence ( 2 ) contains a plurality of semiconductor layers ( 3, 4, 5, 6, 7 ) of Al 1−y Ga y As 1−x Px with 0≦x≦1 and 0≦y≦1, the phosphorus component x in a number of the semiconductor layers respectively being greater than in a neighboring semiconductor layer lying thereunder in the direction of growth. Such a semiconductor substrate may be advantageously used as a quasi-substrate substrate ( 8 ) for growing further semiconductor layers ( 28 ) which have a smaller lattice constant than GaAs. |