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 substrate having a via;
an ohmic contact layer disposed in the via;
an n+ semiconducting buffer layer disposed on the ohmic contact layer;
an n− semiconducting layer disposed on the n+ layer;
a semiconducting barrier layer disposed on the n− layer; and
a Schottky metal layer disposed on the barrier layer.
2. The diode of claim 1 , wherein the n+ layer, the n− layer, and the barrier layer comprises Group III nitrides.
3. The diode of claim 1 , wherein the Schottky metal layer is selected from the group consisting of Cr, Fe, Mn, Nb, Ni, NiCr, Sn, Ta, Ti, Ge, and W.
4. The diode of claim 1 , wherein the Schottky metal layer comprises Cr, Ge or Mn.
5. A diode, comprising:
a SiC substrate having a via;
an ohmic contact disposed in the via;
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 said ohmic contact;
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 n+ 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 n− layer; and
a Schottky metal layer disposed on the barrier layer.