Results are obtained from the experimental studies (atomic force and transmission microscopy) of the influence of III/V flux ratio on the topography and internal structure of LT MBE films of InGaAs and GaAs. The layers are shown to contain both the surface growth defects — the volcano-like pits and microdrops of III group elements, and the bulk defects — dislocations, stacking faults, microtwins, and phase microheterogeneities. A high-temperature annealing results in the additional formation of thermal etching pits at the surface and the nanosized arsenic clusters in the bulk. The origin of the defects is discussed.