VCSELs with improved optical and electrical confinement

A method for manufacturing an optoelectronic device, the method comprising:

• depositing a first set of epitaxial layers on an area of a semiconductor substrate to define a lower distributed Bragg-reflector (DBR) stack;
• depositing a second set of epitaxial layers over the first set, defining a quantum well structure;
• depositing a third set of epitaxial layers over the second set, defining an upper DBR stack, and including a confinement layer, comprising a semiconductor material, within the upper DBR stack;
• etching the third set of epitaxial layers to define a mesa having sides that are perpendicular to the epitaxial layers and extend from an upper surface of the upper DBR stack and terminate at the confinement layer;
• coating the sides of the mesa with a dielectric coating;
• after coating the sides of the mesa, processing the confinement layer so as to convert a peripheral part of the confinement layer to a dielectric material, while leaving the semiconductor material in a central part of the confinement layer, surrounded by the peripheral part;
• and coupling electrodes to the epitaxial layers so as to apply an excitation current to the quantum well structure;
• wherein the thickness of the confinement layer exceeds 50 nm.