Ultra-high Be doping of Ga0.47In0.53 As layers grown by gas source molecular beam epitaxy has shown that for each growth temperature, there exists a maximum hole concentration (≥1×1020cm-3). Increasing the Be flux above that which produces the maximum hole concentration results in a degradation of the crystalline quality of the films. The degradation of film quality results from precipitation of a Be-rich phase on the surface during growth and nucleation of dislocations at each precipitate. Below that concentration, some of the Be segregates and floats on the growing surface.