LARGE PERIODIC POTENTIAL UNDER LATERAL SURFACE SUPERLATTICES FABRICATED FROM HETEROEPITAXIAL STRESSOR LAYERS

We have fabricated lateral surface superlattices by etching a strained layer of In0.2Ga0.8As near the surface of a heterostructure. This pro vides strong modulation of the electron gas while retaining a high ele ctron mobility. The potential arises mainly from strain and the piezoe lectric effect, which depends on orientation, and from the change in t he surface profile. The fundamental components of these two contributi ons cancel in one orientation to leave a dominant second harmonic. Thi s effectively halves the period of the superlattice from its lithograp hic value and provides a promising technique for creating potentials w ith a period comparable to the Fermi wavelength. (C) 1998 American Ins titute of Physics. [S0003-6951(98)00936-X].