Method of creation of low-defects A3B5 semiconductor heterostructures by layer-by-layer monocrystal assembly. Raw materials (Ga, As, Al, In or dopants) are evaporated in ultrahigh vacuum conditions from effusion cells. We are experienced in growth of InGaAs/GaAs and GaAs/AlGaAs quantum wells with inhomogeneous broadening lower that radiative linewidth of excitonic resonance. Other possible structures: Bragg mirrors and microcavities, planar waveguides, thick quantum wells, special profile quantum wells (triangular, parabolic etc.)