Semiconductor device having ohmic recessed electrode
The present invention provides a semiconductor device having a recess-structured ohmic electrode, in which the resistance is small and variation in the resistance value caused by manufacturing irregularities is small. In the semiconductor device of the present invention, a two-dimensional electron gas layer is formed on the interface between a channel-forming layer and a Schottky layer by electrons supplied from the Schottky layer. The ohmic electrode comprises a plurality of side faces in ohmic contact with the two-dimensional electron gas layer. At least a part of side faces of the ohmic electrodes are non-parallel to a channel width direction. In a preferred embodiment of the present invention, the side faces have a saw tooth form or a comb tooth form. Since the contact area between the ohmic electrode and the two-dimensional electron gas layer is increased, ohmic resistance is reduced.
1. A semiconductor device comprising:
a channel-forming layer formed on a semiconductor substrate;
a Schottky layer formed on said channel-forming layer;
a two-dimensional electron gas layer formed on an interface between said Schottky layer and said channel-forming layer by an electron supplied to said channel-forming layer from said Schottky layer;
a gate electrode formed on said Schottky layer via a cap layer; and
a recess-structured ohmic electrode containing a plurality of side faces which are in ohmic contact with said two-dimensional electron gas layer and non-parallel to a channel width direction;
wherein said ohmic electrode comprises a plurality of lower portion electrodes formed in a columnar shape, and an upper portion electrode formed so as to be electrically connected to all of said lower portion electrodes.
2. The semiconductor device according to claim 1 , wherein said lower portion electrodes are disposed in a matrix form.
3. The semiconductor device according to claim 1 , wherein said lower portion electrodes are square columns.
4. The semiconductor device according to claim 1 , wherein said lower portion electrodes are circular columns.