We report very small interdiffusion and surface segregation of Si in δ-doped GaAs, A10.3Gao.7As and Quantum Wells grown at 580 C by Gas Source Molecular Beam Epitaxy. Capacitance-Voltage profiles of δ-doped layers are 38 Å wide for growth at 580 C and further, insignificant profile narrowing is observed at 530C and below. Much wider profiles are observed at equivalent substrate temperature for As4
growth. Atomic diffusion of Si in δ-doped Al0.3Ga0.7As is found to have a rate of D0=5× 10−cm2/sec with an activation energy of 1.8 eV.