GaN-based trench metal oxide Schottky barrier diode and preparation method therefor
The invention relates to a GaN-based trench metal oxide Schottky barrier diode and a preparation method therefor. The device structure from bottom to top includes: an ohmic contact metal layer covering a substrate i.e., cathode; a GaN self-supporting substrate; an n-type lightly doped epitaxial layer; a p-type high-concentration GaN layer arranged in parallel; a dielectric layer in the trench; a metal layer convering the upper surface of the device i.e., the anode. The p-type high-concentration GaN layer with high carrier concentration can be obtained by using a selective area epitaxial method to form the p-type high-concentration GaN layer. Then the dielectric layer is deposited, and a contact hole is provided on the dielectric layer, subsequently the anode metal is connected to the p-type high-concentration GaN layer through the contact hole, forming the ohmic contact.
1 . A GaN-based trench metal oxide Schottky barrier diode, the GaN-based trench metal oxide Schottky barrier diode from top to bottom comprises: a cathode covering a substrate; the substrate; an n-type lightly doped epitaxial layer; a p-type high-concentration GaN layer located in a bottom of a trench, a dielectric layer on an inner surface of the trench; an anode located on an upper surface of the GaN-based trench metal oxide Schottky barrier diode, wherein a plurality of parallel arranged trench structures are formed on a surface of the n-type lightly doped epitaxial layer,
wherein the dielectric layer covers on an inner wall of the trench and located above the p-type high-concentration GaN layer, and a window is provided on a middle position above the p-type high-concentration GaN layer, and
wherein a tilt angle of a mesa of the GaN-based trench metal oxide Schottky barrier diode is less than 90 degree, and the trench is fully filled with the anode.
2 . The GaN-based trench metal oxide Schottky barrier diode according to claim 1 , wherein the p-type high-concentration GaN layer is also provided on a side wall of the trench.
3 . The GaN-based trench metal oxide Schottky barrier diode according to claim 1 , wherein the substrate is an n-type GaN self-supporting substrate, a resistivity range of the substrate is 0.001 Ω·cm to 0.05 Ω·cm, a thickness of the substrate is 350 μm to 400 μm, the n-type lightly doped epitaxial layer is an unintentionally doped epitaxial layer, Si-doped epitaxial layer, or As-doped epitaxiy layer; a thickness of the n-type lightly doped epitaxial layer is 1 μm to 30 μm, and a doping concentration of the n-type lightly doped epitaxial layer is 1×10 14 cm −3 to 5×10 17 cm −3 ; the p-type high-concentration GaN layer is p-GaN material formed by epitaxy, a thickness of the p-type high-concentration GaN layer is 0.2 μm to 2 μm, a hole concentration of the p-type high-concentration GaN layer is 1×10 16 cm −3 to 1×10 19 cm −3 ; the dielectric layer is SiO 2 , Al 2 O 3 , Si 3 N 4 , or HfO 2 , and a thickness of the dielectric layer is 0.05 μm to 0.6 μm; a material of the cathode is any one of Ti/Al/Ni/Au alloy, Ti/Al/Ti/Au alloy, Ti/Al/Mo/Au alloy, and Ti/Al/Ti/TiN alloy, and a material of the anode is one of Ni, Au, Be, Pt and Pd or a stacking structure of Ni, Au, Be, Pt and Pd.