GROWTH OF HIGHLY UNIFORM EPITAXIAL LAYERS OVER MULTIPLE SUBSTRATES BY MOLECULAR-BEAM EPITAXY

A new MBE system with a 190 mm diam. rotating holder is introduced. Seven 2 inch diam. GaAs wafers or three-3-inch diam. wafers can be simultaneously mounted on that holder. The uniform area with the acceptable variation of less than plus or minus 1% was represented as an empirical equation by using the system geometry of the effusion cells and substrate holder. The uniformity of the thickness and carrier concentration of Si-doped GaAs and Al//xGa//1// minus //xAs layers grown by this MBE system were within plus or minus 1% over a diam. of 180 mm. A high uniformity and high mobility two-dimensional electron gas in a selectively doped GaAs/N-Al//xGa//1// minus //xAs heterostructure was obtained. The density of heterostructure surface defects larger than 1 mu m**2 was reduced to less than 380 cm** minus **2. Oval defects, originating in the Ga source, were reduced to a density of less than 40 cm** minus **2.