III-nitride LED with tunnel junction

1. A method of forming a III-Nitride based device comprising:

depositing first layers by metal-organic chemical vapor deposition (MOCVD) on a substrate, wherein said first layers comprise heavily n-doped layers of III-Nitride material at a doping concentration of at least 2E19·cm−3; and

depositing epitaxial second layers over said first layers by at least one of sputtering, plasma deposition, pulsed laser deposition, or liquid phase epitaxy, wherein said second layers comprise heavily p-doped III-Nitride material at a doping concentration of at least 2E19·cm−3, wherein said first and second layers form at least partially a tunnel junction such that carriers tunnel from the first layers to the second layers, wherein said tunnel junction has a specific contact resistance lower than 5E-3 Ohm·cm2 at a current density of 100 A·cm−2.

2. The method of claim 1 , wherein said first layers have a lower defect concentration than said second layers.

3. The method of claim 2 , wherein said first layers have a lower defect concentration than said second layers such that, said first layers have a first average defect concentration, said second layers have a second average defect concentration, and said second average defect concentration is at least twice said first average defect concentration.

4. The device of claim 3 , wherein said second average defect concentration is one of: an impurity concentration higher than 1E17 cm−3, or an intrinsic defect concentration higher than 1E16 cm−3.

5. The method of claim 3 , wherein at least one layer of the second layer has an extrinsic defect comprising one of the following species: O, C, If, a transition metal, a metal; or an extrinsic defect selected form: a Ga or N vacancy, a Ga or N interstitial.

6. The method of claim 2 , wherein the deposition of said second layers is epitaxial such that at least one of the following is true:

wherein said first layers are characterized by a first threading dislocation density (TDD) and said second layers are characterized by a second TDD, wherein said second TDD is no more than twice said first TDD;

wherein said first layers are characterized by a first X-ray diffraction (XRD) rocking curve full width at half maximum (FWHM) and said second layers are characterized by a second XRD rocking curve FWHM, wherein said second FWHM is no more than twice said first FWHM.

7. The method of claim 1 , wherein a last layer of said first layers has a lower defect concentration than a first layer of said second layers.

8. The method of claim 1 , wherein said tunnel junction is defined either within said second layers or at said interface of said first layers and said second layers.

9. The method of claim 1 , wherein said tunnel junction is defined at said interface of said first layers and said second layers.

10. The method of claim 1 , wherein said second layers are deposited by sputtering and at least a portion of sputtering occurs in an ambient comprising nitrogen.

11. The method of claim 1 , further comprising growing third layers by MOCVD on said second layers.