Vertical cavity surface emitting laser diode (VCSEL) with tunnel junction

A vertical cavity surface emitting laser diode (VCSEL), comprising:

• a GaAs substrate;
• and
• an epitaxial structure positioned on the GaAs substrate, wherein the epitaxial structure comprises:
• an oxidation layer;
• and
• a tunnel junction comprising a n-type semiconductor layer and being positioned above or below the oxidation layer, wherein the n-type semiconductor layer including InGaAs is doped with tellurium and/or selenium, and the n-type semiconductor layer is not latticed-matched to the GaAs substrate such that the n-type semiconductor layer has stress relative to the GaAs substrate, wherein the tunnel junction further comprises a p-type semiconductor layer, the p-type semiconductor layer including AlGaAs is doped with carbon, and a carbon doping concentration of the p-type semiconductor layer is greater than 8×1019/cm3,
• wherein the epitaxial structure comprises an active region, the active region comprising a plurality of active layers, and the tunnel junction and the oxidation layer are provided between two adjacent active layers of the plurality of active layers so that the two adjacent active layers are connected in series through the tunnel junction,
• wherein the oxidation layer comprises an optical aperture, the optical aperture is formed after the epitaxial structure is subject to an oxidation process.