Disclosed herein is a semiconductor structure including: (i) a monocrystalline substrate having a top surface, (ii) a non-crystalline structure overlying the monocrystalline substrate and including an opening having a width smaller than 10 microns and exposing part of the top surface of the monocrystalline substrate. The semiconductor structure also includes (iii) a buffer structure having a bottom surface abutting the part and a top surface having less than 108 threading dislocations per cm2, the buffer structure being made of a material having a first lattice constant. The semiconductor structure also includes (iv) one or more group IV monocrystalline structures abutting the buffer structure and that are made of a material having a second lattice constant, different from the first lattice constant.