Low voltage diode with reduced parasitic resistance and method for fabricating
View Patent ↗A method of making a diode begins by depositing an Al x Ga 1-x N nucleation layer on a SiC substrate, then depositing an n+ GaN buffer layer, an n− GaN layer, an Al x Ga 1-x N barrier layer, and an SiO 2 dielectric layer. A portion of the dielectric layer is removed and a Schottky metal deposited in the void. The dielectric layer is affixed to the support layer with a metal bonding layer using an Au—Sn utectic wafer bonding process, the substrate is removed using reactive ion etching to expose the n+ layer, selected portions of the n+, n−, and barrier layers are removed to form a mesa diode structure on the dielectric layer over the Schottky metal, and an ohmic contact is deposited on the n+ layer.
1. A diode, comprising:
a conductive support layer;
a Schottky metal layer on the conductive support layer;
a semiconducting barrier layer on the Schottky layer opposite the conductive support layer;
an n− semiconducting layer on the barrier layer opposite the Schottky layer;
an n+ semiconducting buffer layer on the n− layer opposite the barrier layer; and
an ohmic contact on the n+ layer opposite the n− layer.
2. The diode of claim 1 , further comprising a metal bonding layer affixing the Schottky layer to the support layer.
3. The diode of claim 1 , wherein the n+ layer, the n− layer, and the barrier layer comprises Group III nitrides.
4. The diode of claim 1 , wherein the Schottky metal is selected from the group consisting of Cr, Fe, Mn, Nb, Ni, NiCr, Sn, Ta, Ti, Ge, and W.
5. The diode of claim 2 , wherein the conductive support layer is metallized Si.
6. A diode, comprising:
a conductive support layer;
a Schottky metal layer;
a metal bonding layer affixing the Schottky layer to the support layer;
a 0-20 Å thick semiconducting barrier layer of Al x Ga 1-x N, with 0.15≦x≦0.45, disposed on the Schottky layer opposite the bonding layer;
an n− semiconducting layer of GaN, between 0.5 and 5 μm thick and doped with an impurity concentration of between 1×10 15 /cm 3 and 1×10 17 /cm 3 , disposed on the barrier layer opposite the Schottky layer;
an n+ semiconducting buffer layer of GaN, between 0.5 and 5 μm thick and doped with an impurity concentration of between 5×10 17 /cm 3 and 5×10 19 /cm 3 , disposed on the n− layer opposite the barrier layer; and
an ohmic contact disposed on the n+ layer opposite the n− layer.
7. The diode of claim 1 , exhibiting a V f of approximately 0.2V.
8. The diode of claim 1 , exhibiting a V f of less than 0.2V.
9. The diode of claim 1 , wherein said n+ semiconducting buffer layer of GaN is between 0.5 and 5 μm thick and doped with an impurity concentration of between 5×10 17 /cm 3 and 5×10 19 /cm 3 .
10. The diode of claim 1 , wherein said n− semiconducting layer of GaN, is between 0.5 and 5 μm thick and doped with an impurity concentration of between 1×10 15 /cm 3 and 1×10 17 /cm 3 .
11. The diode of claim 1 , wherein said semiconducting barrier layer comprises Al x Ga 1-x N and is between 0-20 Å thick, with 0.15≦x≦0.45.
12. The diode of claim 6 , wherein the Schottky metal comprises a material from the group consisting of Cr, Fe, Mn, Nb, Ni, NiCr, Sn, Ta, Ti, Ge, W and combinations thereof.
13. The diode of claim 6 , wherein the conductive support layer comprises a metallized layer.
14. The diode of claim 6 , wherein the conductive support layer is metallized Si.
15. The diode of claim 6 , exhibiting a V f of approximately 0.2V.
16. The diode of claim 6 , exhibiting a V f of less than 0.2V.
17. The diode of claim 1 , further comprising a bonding layer between the conductive support layer and the Schottky metal layer.