A method for obtaining at least one semi-polar nitride layer obtained from a gallium and nitrogen based material on an upper surface of a crystalline substrate of cubic symmetry, the method comprising: - etching a plurality of parallel grooves from the upper surface of the crystalline substrate, each groove comprising at least two opposed inclined facets (310, 311), at least one of the two opposed facets (310, 311) having a crystalline orientation <111>; - forming a mask above the upper surface of the crystalline substrate such that the facets opposite to the facets having the crystalline orientation <111> are masked and that said facets having the crystalline orientation <111> are not masked; and - after the step of forming the mask, forming the semi-polar nitride layer by epitaxial growth from the non-masked facets having the crystalline orientation <111>; characterized in that the step of forming the semi-polar nitride layer comprises at least the following steps: - at least one first epitaxial growth phase, carried out from the non-masked facets having the crystalline orientation <111> so as to form a seed in a plurality at least of parallel grooves; - interrupting the first epitaxial growth phase when the seed has an inclined facet having a crystalline orientation and an upper facet having a crystalline semi-polar orientation; - a step of surface treatment comprising a modification of an upper portion of the seed by placing the seed in presence with at least one gas comprising silicon (Si) so as to form on the surface of the seed a modified portion comprising silicon (Si); and - at least one second epitaxial growth phase of the material, carried out from the inclined facet having a crystalline orientation, the second epitaxial growth phase being continued until coalescence of seeds of adjacent parallel grooves. - etching a plurality of parallel grooves from the upper surface of the crystalline substrate, each groove comprising at least two opposed inclined facets (310, 311), at least one of the two opposed facets (310, 311) having a crystalline orientation <111>; - forming a mask above the upper surface of the crystalline substrate such that the facets opposite to the facets having the crystalline orientation <111> are masked and that said facets having the crystalline orientation <111> are not masked; and - after the step of forming the mask, forming the semi-polar nitride layer by epitaxial growth from the non-masked facets having the crystalline orientation <111>; - at least one first epitaxial growth phase, carried out from the non-masked facets having the crystalline orientation <111> so as to form a seed in a plurality at least of parallel grooves; - interrupting the first epitaxial growth phase when the seed has an inclined facet having a crystalline orientation and an upper facet having a crystalline semi-polar orientation; - a step of surface treatment comprising a modification of an upper portion of the seed by placing the seed in presence with at least one gas comprising silicon (Si) so as to form on the surface of the seed a modified portion comprising silicon (Si); and - at least one second epitaxial growth phase of the material, carried out from the inclined facet having a crystalline orientation, the second epitaxial growth phase being continued until coalescence of seeds of adjacent parallel grooves.