Wide bandgap semiconductor device
A wide bandgap semiconductor device includes a first conductive type high-concentration wide bandgap semiconductor substrate, a first conductive type low-concentration wide bandgap semiconductor deposited film which is formed on the semiconductor substrate, a metal film which is formed on the semiconductor deposited film so that a Schottoky interface region is formed between the metal film and the semiconductor deposited film, and a second conductive type region which is formed in a region of the semiconductor deposited film corresponding to a peripheral portion of the metal film, wherein the Schottoky interface region in the semiconductor deposited film is surrounded by the second conductive type region so that periodic island regions are formed in the Schottoky interface region.
1. A wide bandgap semiconductor device, comprising:
a first conductive type high-concentration wide bandgap semiconductor substrate;
a first conductive type low-concentration wide bandgap semiconductor deposited film which is formed on the first conductive type high-concentration wide bandgap semiconductor substrate;
a metal film which is formed on the first conductive type low-concentration wide bandgap semiconductor deposited film so that a Schottoky interface region is formed between the metal film and the first conductive type low-concentration wide bandgap semiconductor deposited film; and
a second conductive type region which is formed in a region of the first conductive type low-concentration wide bandgap semiconductor deposited film corresponding to a peripheral portion of the metal film;
wherein:
the Schottoky interface region in the first conductive type low-concentration wide bandgap semiconductor deposited film is surrounded by the second conductive type region so that periodic island regions are formed in the Schottoky interface region;
the relation S2×N2≧S1×N1 is established when S1 designates a contact area between the metal film and the island regions, N1 designates an impurity concentration of the first conductive type low-concentration wide bandgap semiconductor deposited film, S2 designates a contact area between the metal film and the second conductive type region and N2 designates an impurity concentration of the second conductive type region;
a width of each of the island regions is not shorter than 1 μm and not longer than 4 μm; and
the second conductive type region is a one region having a uniform depth, has a wider width from an outer perimeter to an outermost perimeter of the island regions than a width of an interval between two island regions, and is surrounded by a floating limiting ring (FLR) structure, a junction termination extension (JTE) structure or a floating plate structure having the second conductive type.
2. The wide bandgap semiconductor device according to claim 1 , wherein: a shape of each of the island regions is a regular polygon.
3. The wide bandgap semiconductor device according to claim 2 , wherein: the wide bandgap semiconductor device includes SiC.
4. The wide bandgap semiconductor device according to claim 2 , wherein: the wide bandgap semiconductor device includes gallium nitride.
5. The wide bandgap semiconductor device according to claim 1 , wherein: a shape of each of the island regions is a circle.
6. The wide bandgap semiconductor device according to claim 5 , wherein: the wide bandgap semiconductor device includes SiC.
7. The wide bandgap semiconductor device according to claim 1 , wherein: the wide bandgap semiconductor device includes SiC.
8. The wide bandgap semiconductor device according to claim 5 , wherein: the wide bandgap semiconductor device includes gallium nitride.
9. The wide bandgap semiconductor device according to claim 1 , wherein: the wide bandgap semiconductor device includes gallium nitride.