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. A method of manufacturing an optoelectronic device that includes an integrated VCSEL and photodiode, the method comprising:
forming a photodiode on a substrate;
forming a transition region on the photodiode;
forming a VCSEL on the transition region; and
forming a first Ohmic contact on the VCSEL and forming a second Ohmic contact on the photodiode so as to short at least a portion of the transition region, wherein one of the first and second Ohmic contacts is electrically coupled to a cathode and the other of the first and second Ohmic contacts is electrically coupled to an anode.
2. The method of claim 1 , wherein forming a photodiode and forming a transition layer comprise:
forming an N type absorption layer on a substrate;
forming a P+ GaAs or AlGaAs layer on the N type absorption layer;
forming a P+ GaAs layer on the P+ AlGaAs layer;
forming a GaAs or AlGaAs layer on the P+ GaAs layer; and
forming an N+ GaAs layer on the AlGaAs layer.
3. The method of claim 2 , wherein forming a wherein forming Ohmic contacts on the optoelectronic device comprises:
etching to the N+ GaAs layer and depositing a Au:Ge contact on the N+ GaAs layer; and
etching to the P+ GaAs layer and depositing a Ti:Au contact on the Au:Ge contact and the P+ GaAs layer.
4. The method of claim 1 , wherein etching to the P+ GaAs layer comprises;
etching away the N+ GaAs layer using a first stop etch; and
etching away the AlGaAs layer using a second stop etch.
5. The method of claim 4 , wherein the first stop etch is citric acid and the second stop etch is dilute hydrofluoric acid.
6. The method of claim 1 , wherein etching to the P+ GaAs layer comprises;
etching away the N+ GaAs layer using a first timed etch; and
etching away the AlGaAs layer using a second timed etch.
7. The method of claim 1 , wherein forming an absorption layer and forming a transition layer comprise:
forming an N type absorption layer on a substrate;
forming a P+ GaAs layer on the N type absorption layer; and,
forming an N+ GaAs layer on the P+ GaAs layer.
8. The method of claim 7 , wherein forming Ohmic contacts on the optoelectronic device comprises:
etching to the N+ GaAs layer using a timed etch and depositing a Au:Ge contact on the N+ GaAs layer; and
etching to the P+ GaAs layer using a timed etch and depositing a Ti:Au contact on the Au:Ge contact and the P+ GaAs layer.
9. The method of claim 1 , wherein the entire transition region is formed over at least a portion of the photodiode.
10. The method of claim 1 , wherein the entire VCSEL is formed over the transition region.
11. The method of claim 1 , wherein the first Ohmic contact is coupled to a cathode of the VCSEL and the second contact is coupled to an anode for the photodiode.
12. The method of claim 1 , wherein the VCSEL includes a third contact that is electrically coupled to the photodiode, the method further comprising applying power to the first and third contacts using a single power supply.
13. The method of claim 12 , wherein the single power supply is a high voltage power supply.
14. The method of claim 13 , further comprising applying a low voltage power to the second Ohmic contact.
15. A device manufactured according to the method of claim 1 .
16. A method of manufacturing an optoelectronic device that includes an integrated VCSEL and photodiode, the method comprising:
forming a photodiode on a substrate;
forming a transition region on the photodiode;
forming a VCSEL on the transition region; and
forming a first Ohmic contact on the cathode of the VCSEL; and
forming a second Ohmic contact on the anode of the photodiode, the first and/or second Ohmic contacts providing a short of at least a portion of the optoelectronic device.