Tunnel junction for GaAs based VCSELs and method therefor
A vertical-cavity surface-emitting laser (VCSEL) has a substrate formed of GaAs. A pair of mirrors is provided wherein one of the pair of mirrors is formed on the substrate. A tunnel junction is formed between the pair of mirrors.
1. A vertical-cavity surface-emitting laser (VCSEL) comprising:
a substrate formed of GaAs;
a pair of mirrors, wherein the pair of mirrors comprises:
a bottom N-type mirror formed on the substrate; and
a top mirror, wherein the top mirror has a bottom section attached to a top section, the top section of the top mirror being an N-type top section and the bottom section being a P-type bottom section;
a tunnel junction formed between the bottom section and the top section of the top mirror, the tunnel junction formed directly on the bottom section of the top mirror, wherein the tunnel junction comprises:
a p-layer formed directly on the bottom section of the top mirror and having a p++ dopant; and
a n-layer formed on the p-layer, wherein Tellurium is used as an n++ dopant in the n-layer;
wherein the p-layer and the n-layer of the tunnel junction are formed of GaAs, AlGaAs, or InGaP; and
wherein the n++ dopant exceeds doping levels of 2E19 cm −3 and the p++ dopant exceeds doping levels greater than 1E20 cm −3 .
2. The VCSEL of claim 1 , wherein Carbon is used as the p++ dopant in the p-layer.
3. The VCSEL of claim 1 , comprising: an active region formed between the pair of mirrors.
4. The VCSEL of claim 3 , comprising:
a metal layer formed on the top section of the top mirror; and
an opening formed in the metal layer.
5. A vertical-cavity surface-emitting laser (VCSEL) comprising:
a substrate;
a first mirror formed on the substrate, the first mirror being a first N-type mirror;
an active region formed on the first mirror;
a second mirror formed above the active region, the second mirror comprising:
a bottom mirror section formed on the active region; and
a top mirror section formed on and attached to the bottom mirror section, the top mirror section being a second N-type mirror; and
a tunnel junction formed directly on the bottom mirror section of the second mirror;
wherein the tunnel junction comprises:
a p-layer formed directly on the bottom mirror section, wherein Carbon is used as a p++ dopant in the p-layer; and
an n-layer formed on the p-layer, wherein Tellurium is used as an n++ dopant in the n-layer and exceeds doping levels of 2E19 cm −3 and carbon is used as the p++ dopant in the p-layer and has doping levels greater than 1E20 cm −3 ;
wherein the p-layer and the n-layer of the tunnel junction are formed of GaAs, AlGaAs, or lnGaP.
6. The VCSEL of claim 5 , comprising:
a metal layer formed on the second mirror; and
an opening formed in the metal layer.
7. The VCSEL of claim 5 , wherein Carbon is used as a p++ dopant in the p-layer.
8. The VCSEL of claim 5 , wherein the substrate is formed of GaAs.