Patent ID: 7652282

Claim:
A semiconductor wafer for use in fabrication of semiconductor devices, the wafer comprising: (A) a substrate; (B) a buffer region formed on the substrate and made from semiconducting compounds, the buffer region comprising: (a) a first multilayered buffer subregion formed on the substrate, the first multilayered buffer subregion comprising alternations of a multi-sublayered first buffer layer and a non-sublayered second buffer layer, each multi-sublayered first buffer layer of the first multilayered buffer subregion comprising alternations of a first and a second buffer sublayer, the first buffer sublayers of the multi-sublayered first buffer layers being each thinner than each non-sublayered second buffer layer and being less in lattice constants than the substrate, the second buffer sublayers of the multi-sublayered first buffer layers being each thinner than each non-sublayered second buffer layer and being intermediate in lattice constants between the first buffer sublayers of the multi-sublayered first buffer layers and the substrate, the non-sublayered second buffer layers of the first multilayered buffer subregion being each thicker than each first and each second buffer sublayer of each multi-sublayered first buffer layer of the first multilayered buffer subregion and being intermediate in lattice constants between the first buffer sublayers of the multi-sublayered first buffer layers and the substrate; and (b) a second multilayered buffer subregion formed on the first multilayered buffer subregion of the buffer region, the second multilayered buffer subregion comprising alternations of a first and a second buffer layer, the first buffer layers of the second multilayered buffer subregion being each thinner than each non-sublayered second buffer layer of the first multilayered buffer subregion and less in lattice constants than the substrate, the second buffer layers of the second multilayered buffer subregion being each thinner than each non-sublayered second buffer layer of the first multilayered buffer subregion and being intermediate in lattice constants between the first buffer layers of the second multilayered buffer subregion and the substrate; and (C) a main semiconductor region of semiconducting compounds formed on the buffer region to provide desired semiconductor devices; (D) the first multilayered buffer subregion of the buffer region being less in mean lattice constants than the main semiconductor region; (E) the second multilayered buffer subregion of the buffer region being intermediate in mean lattice constants between the first multilayered buffer subregion of the buffer region and the main semiconductor region.