III-nitride based on semiconductor device with low-resistance ohmic contacts
View Patent ↗The present invention utilizes high-indium-content In x Ga 1-x N islands (0<x≦1) formed on a top of a p-type GaN based layer to reduce contact resistance between an electrode and the p-type GaN based layer. These In x Ga 1-x N islands serve as channels for electrical current to flow through and dramatically reduce the contact resistance between the electrode and the p-type GaN based layer so as to improve device performance. This structure of In x Ga 1-x N islands can be applied to all III-nitride based electronic and optoelectronic devices requiring good p-type ohmic contacts to improve device performance.
1. A GaN based semiconductor device, comprising:
a P-type GaN based layer;
a structure of compressively strained In x Ga 1-x N islands directly formed on a Ga-face of said P-type GaN based layer, wherein 0<x≦1; and
an electrode formed directly on said compressively strained In x Ga 1-x N island.
2. The GaN based semiconductor device as claimed in claim 1 , wherein said compressively strained In x Ga 1-x N islands are nano-sized In x Ga 1-x N islands.
3. The GaN based semiconductor device as claimed in claim 2 , wherein said In x Ga 1-x N islands have lateral sizes between 1 nm to 200 nm.
4. The GaN based semiconductor device as claimed in claim 3 , wherein said In x Ga 1-x N islands have vertical sizes between 0.5 nm to 10 nm.
5. The GaN based semiconductor device as claimed in claim 2 , wherein said In x Ga 1-x N islands have vertical sizes between 0.5 nm to 10 nm.
6. The GaN based semiconductor device as claimed in claim 1 , wherein said GaN based semiconductor device includes a light emitting diode, a laser diode or a transistor.
7. The GaN based semiconductor device as claimed in claim 1 , wherein said P-type GaN based layer includes GaN, AlN, AlGaN, InGaN or AlInGaN.
8. The GaN based semiconductor device as claimed in claim 1 , wherein said electrode comprises at least one metal selected from a group consisting of Ni, Au, Al, Ti, Pt, Pd, Ag, Tl and Cu.
9. The GaN based semiconductor device as claimed in claim 1 , wherein said electrode comprises at least one alloy selected from a group consisting of Ni/Au, Pd/Au, Tl/Au and Cu/Au.
10. The GaN based semiconductor device as claimed in claim 1 , wherein said electrode comprises at least one layer of conductive transparent oxide including at least one of In, Sn, Cd and Zn.
11. A The GaN based semiconductor device as claimed in claim 1 , wherein said structure of compressively strained In x Ga 1-x N islands comprises a structure of compressively strained high-indium-content IN x Ga 1-x N islands.
12. A method for fabricating a GaN based semiconductor device, comprising:
forming a P-type GaN based layer over a substrate;
forming a structure of compressively strained In x Ga 1-x N islands directly on a Ga-face of said P-type GaN based layer, wherein 0<x≦1; and
forming an electrode directly on said compressively strained In x Ga 1-x N islands.
13. The method as claimed in claim 12 , wherein said compressively strained In x Ga 1-x N islands is pseudomorphically grown on said P-type GaN based layer.
14. The method as claimed in claim 13 , wherein said compressively strained In x Ga 1-x N islands are formed by an MOCVD (Metal-Organic Chemical Vapor Deposition) method.
15. The method as claimed in claim 12 , wherein said P-type GaN based layer includes GaN, AlN, AlGaN, InGaN or AlInGaN.
16. The method as claimed in claim 12 , wherein said substrate includes sapphire, SiC, ZnO, Si, GaP or GaAs.
17. The method as claimed in claim 12 , wherein said forming a structure of compressively strained In x Ga 1-x N islands comprises forming a high-indium-content IN x Ga 1-x N islands.