Growth of highly uniform epitaxial layers over multiple substrates by molecular beam epitaxy

A new MBE system with a 190 mm diameter rotating holder is introduced for the first time. Seven 2 inch diameter GaAs wafers or three-3-inch diameter wafers can be simultaneously mounted on that holder. The uniform area with the acceptable variation of less than ±1% was successfully 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 AlxGa1−xAs layers grown by this MBE system were within ±1% over a diameter of 180 mm. A high uniformity and high mobility two-dimensional electron gas in a selectively doped GaAs/N-AlxGa1−xAs heterostructure was obtained. The density of heterostructure surface defects larger than 1 μm2 was reduced to less than 380 cm-2. In particular, oval defects, originating in the Ga source, were reduced to a density of less than 40 cm-2.