Nitride semiconductor device such as transverse power FET for high frequency signal amplification or power control
A nitride semiconductor device according to one embodiment of the present invention includes: a non-doped first aluminum gallium nitride (Al x Ga 1-x N (0≦x≦1)) layer which is formed as a channel layer; a non-doped or n type second aluminum gallium nitride (Al y Ga 1-y N (0≦y≦1, x <y)) layer which is formed on the first aluminum gallium nitride layer as a barrier layer; an aluminum nitride (AlN) film which is formed on the second aluminum gallium nitride layer as a gate insulating film lower layer; an aluminum oxide (AL 2 O 3 ) film which is formed on the aluminum nitride film as a gate insulating film upper layer; a source electrode and a drain electrode which are formed as first and second main electrodes to be electrically connected to the second aluminum gallium nitride layer, respectively; and a gate electrode which is formed on the aluminum oxide film as a control electrode.
1. A nitride semiconductor device comprising:
a non-doped first aluminum gallium nitride (Al x Ga 1-x N (0≦x≦1)) layer which is formed as a channel layer;
a non-doped or n type second aluminum gallium nitride (Al y Ga 1-y N (0≦y 1, x≦y)) layer which is formed on the first aluminum gallium nitride layer as a barrier layer;
an aluminum nitride (AlN) film which is formed on the second aluminum gallium nitride layer as a gate insulating film lower layer, the aluminum nitride film being selected from a polycrystalline film and an amorphous film;
an aluminum oxide (Al 2 O 3 ) film which is formed on the aluminum nitride film as a gate insulating film upper layer;
a source electrode and a drain electrode which are formed as first and second main electrodes to be electrically connected to the second aluminum gallium nitride layer, respectively; and
a gate electrode which is formed on the aluminum oxide film as a control electrode.
2. The nitride semiconductor device according to claim 1 , further comprising:
an insulating film which is formed to cover the gate electrode; and
a field plate electrode which is formed on the insulating film to cover the gate electrode and is electrically connected to the source electrode.
3. The nitride semiconductor device according to claim 2 , further comprising:
a second field plate electrode which is formed on the insulating film to cover a region positioned in the vicinity of the drain electrode between the drain electrode and the gate electrode and is electrically connected to the drain electrode.
4. The nitride semiconductor device according to claim 1 , further comprising:
a gallium nitride layer which is formed to be sandwiched between the second aluminum gallium nitride layer and the aluminum nitride film.
5. The nitride semiconductor device according to claim 4 , wherein the gallium nitride layer is selectively formed on a region between the second aluminum gallium nitride layer and the aluminum nitride film.
6. The nitride semiconductor device according to claim 5 , wherein a conductive type of the gallium nitride layer is a p type.
7. The nitride semiconductor device according to claim 1 , further comprising:
gallium nitride layers which are formed to be sandwiched between the second aluminum gallium nitride layer and the source electrode and between the second aluminum gallium nitride layer and the drain electrode.
8. The nitride semiconductor device according to claim 1 , wherein the aluminum oxide film is a polycrystalline film.
9. The nitride semiconductor device according to claim 1 , wherein the aluminum oxide film is an amorphous film.
10. A nitride semiconductor device comprising:
a non-doped first aluminum gallium nitride (Al x Ga 1-x N (0≦x≦1)) layer which is formed as a channel layer;
a non-doped or n type second aluminum gallium nitride (Al y Ga 1-y N (0≦y≦1, x <y)) layer which is formed on the first aluminum gallium nitride layer as a barrier layer;
a gate electrode which is formed on a portion of the second aluminum gallium nitride layer as a control electrode;
an aluminum nitride (AlN) film which is formed on the second aluminum gallium nitride layer to cover the gate electrode as an insulating film lower layer, the aluminum nitride film being selected from a polycrystalline film and an amorphous film;
an aluminum oxide (Al 2 O 3 ) film which is formed on the aluminum nitride film as an insulating film upper layer; and
a source electrode and a drain electrode which are formed as first and second main electrodes to be electrically connected to the second aluminum gallium nitride layer, respectively.
11. The nitride semiconductor device according to claim 10 , further comprising:
an insulating film which is formed on the aluminum oxide film; and
a field plate electrode which is formed on the insulating film to cover the gate electrode and is electrically connected to the source electrode.
12. The nitride semiconductor device according to claim 11 , further comprising:
a second field plate electrode which is formed on the insulating film to cover a region positioned in the vicinity of the drain electrode between the drain electrode and the gate electrode and is electrically connected to the drain electrode.
13. The nitride semiconductor device according to claim 10 , further comprising:
a gallium nitride layer which is formed to be sandwiched between the second aluminum gallium nitride layer and the gate electrode.
14. The nitride semiconductor device according to claim 13 , wherein a conductive type of the gallium nitride layer is a p type.
15. The nitride semiconductor device according to claim 10 , wherein the aluminum oxide film is a polycrystalline film.
16. The nitride semiconductor device according to claim 10 , wherein the aluminum oxide film is an amorphous film.