Integrated light emitting device and photodiode with ohmic contact
View Patent ↗Optoelectronic device including integrated light emitting device and photodiode. The optoelectronic device includes a light emitting, device such as a vertical cavity surface emitting laser (VCSEL) or resonant cavity light emitting diode (RCLED). A photodiode is also included in the optoelectronic device. Between the light emitting device and the photodiode is a transition region. At least part of the transition region is shorted. A metal contact provides a contact to both the light emitting device and the photodiode.
1. An optoelectronic device comprising:
a VCSEL, the VCSEL comprising:
a VCSEL top mirror;
an active region coupled to the VCSEL top mirror; and
a VCSEL bottom mirror;
a transition region coupled to the VCSEL;
a photodiode coupled to the transition region; and
metal coupled to the optoelectronic device so as to short at least a portion of the transition region and to provide Ohmic contacts to the VCSEL and photodiode, wherein the transition region and photodiode comprise:
an N+ GaAs layer coupled to the VCSEL;
a GaAs or AlGaAs layer coupled to the N+ GaAs layer;
a P+ GaAs layer coupled to the AlGaAs layer;
a P+ GaAs or AlGaAs layer coupled to the P+ GaAs layer; and
an N type absorption layer coupled to the P+ GaAs or AlGaAs layer.
2. The optoelectronic device of claim 1 , wherein the AlGaAs layer is about λ/4.
3. The optoelectronic device of claim 1 , wherein the AlGaAs layer is undoped.
4. The optoelectronic device of claim 1 , wherein the AlGaAs layer is P-type.
5. The optoelectronic device of claim 1 , wherein the AlGaAs layer is N-type.
6. The optoelectronic device of claim 1 , wherein the metal comprises Au:Ge coupled to the N+ GaAs layer and Ti:Au coupled to the P+ GaAs layer and the Au:Ge.
7. The optoelectronic device of claim 1 , wherein the transition region is disposed over at least a portion of the photodiode.
8. The optoelectronic device of claim 1 , wherein the VCSEL is disposed over at least a portion of the transition region.
9. The optoelectronic device of claim 8 , wherein the transition region is disposed over at least a portion of the photodiode.
10. An optoelectronic device comprising:
a VCSEL, the VCSEL comprising:
a VCSEL top mirror;
an active region coupled to the VCSEL top mirror; and
a VCSEL bottom mirror;
a transition region coupled to the VCSEL;
a photodiode coupled to the transition region; and
metal coupled to the optoelectronic device so as to short at least a portion of the transition region and to provide Ohmic contacts to the VCSEL and photodiode, wherein the transition region and photodiode comprise:
an N+ GaAs layer coupled to the VCSEL, wherein the N+ GaAs layer comprises a thickness of about λ/4;
an AlGaAs layer coupled to the N+ GaAs layer;
a P+ GaAs layer coupled to the AlGaAs layer; and
an N type absorption layer.
11. The optoelectronic device of claim 10 , wherein the P+ GaAs layer comprises a thickness of about λ/4.
12. The optoelectronic device of claim 10 , the transition region further comprising a transparent P+ AlGaAs layer coupled to the P+ GaAs layer the transparent P+ AlGaAs layer comprising a thickness that is about λ/4.
13. The optoelectronic device of claim 12 , wherein the transparent P+ AlGaAs layer comprises P+ Al 0.15 Ga 0.85 As.
14. The optoelectronic device of claim 10 , wherein the AlGaAs layer comprises an AlAs composition of about 85% to 100%.