Method for flattening a surface on an epitaxial lateral growth layer

A method for manufacturing a semiconductor layer, comprising:

• preparing a plurality of epitaxial lateral overgrowth (ELO) III-nitride layers grown on or above a growth restrict mask on a substrate, wherein adjacent ones of the plurality of ELO III-nitride layers are separated from each other by a no-growth region;
• removing of the growth restrict mask in the no-growth region, wherein the growth restrict mask does not remain between adjacent ones of the plurality of ELO III-nitride layers and a portion of the growth restrict mask remains between the substrate and the plurality of ELO III-nitride layers;
• and
• growing a plurality of III-nitride device layers on or above the plurality of ELO III-nitride layers and the substrate, wherein adjacent ones of the plurality of III-nitride device layers are separated from each other by the no-growth region;
• wherein:
• the growth restrict mask is removed after growing the plurality of ELO III-nitride layers and before growing at least some of the plurality of III-nitride device layers;
• and
• the plurality of ELO III-nitride layers are grown to a height that prevents growth of a bottom layer in the no-growth region where the growth mask is removed, during the growth of the III-nitride device layers.