Method for electrochemically etching a semiconductor structure

A semiconductor structure comprising:

• a porous nanostructured portion comprising a plurality of sub-surface nanostructures of a first III-V semiconductor material;
• and
• a surface layer of a second III-V semiconductor material, the surface layer having a charge carrier density of less than 5×1017 cm−3;
• in which the surface layer covers the porous nanostructured portion comprising the sub-surface nanostructures;
• and
• in which the porous nanostructured portion is a porous quantum structure, the porous nanostructured portion having one or more dimensions of less than or equal to 0.25 nm, or 0.5 nm, or 1 nm, or 2 nm, or 3 nm, or 5 nm, or 8 nm, or 10 nm, or 12 nm.

A semiconductor structure comprising:

• a porous nanostructured portion comprising a plurality of sub-surface nanostructures of a first III-V semiconductor material;
• and
• a surface layer of a second III-V semiconductor material, the surface layer having a charge carrier density of less than 5×1017 cm−3;
• in which the surface layer covers the porous nanostructured portion comprising the sub-surface nanostructures;
• and
• in which the semiconductor structure is an LED structure, and the porous nanostructured portion is a porous quantum well.