Method of fabricating a diffraction grating and a distributed feedback

Abstract

A quantum wire structure includes a substrate of a first semiconductor having a surface and a first band gap energy; a layer of a second semiconductor having a second band gap energy and including second semiconductor elements disposed on the surface of the substrate spaced apart in a pattern at an interval of no more than 100 nm, each second semiconductor element having a trapezoidal cross-section transverse to the surface of the substrate and including an upper surface generally parallel to the surface of the semiconductor substrate and sloped surfaces oriented so that a third semiconductor does not grow on the sloped surfaces; a layer of a third semiconductor having a third band gap energy smaller than the first and second band gap energies disposed on the upper surfaces of the second semiconductor elements and on the surface of the substrate between adjacent second semiconductor elements but not on the sloped surfaces; and a layer of a fourth semiconductor having a fourth band gap energy larger than the third band gap energy disposed on and burying the layers of the second and third semiconductors.