Nitride semiconductor device

Abstract

A nitride semiconductor device includes a first impurity layer made of an Al 1-X Ga X N (0<X≤1) based material and containing a first impurity with which a depth of an acceptor level from a valence band (E T -E V ) is made not less than 0.3 eV but less than 0.6 eV, an electron transit layer formed on the first impurity layer, an electron supply layer formed on the electron transit layer, agate electrode formed on the electron transit layer, and a source electrode and a drain electrode formed such that the source electrode and the drain electrode sandwich the gate electrode and electrically connected to the electron supply layer.

1 - 20 . (canceled) 
     
     
         21 . A nitride semiconductor device comprising:
 a first impurity layer made of an Al 1-X Ga X N (0<X≤1) based material and containing Zn as a first impurity;   an electron transit layer formed on the first impurity layer;   an electron supply layer formed on the electron transit layer;   an insulating layer formed over the electron transit layer having a portion being in contact with the electron transit layer through the electron supply layer;   a gate electrode formed on the insulating layer;   a second insulating layer covering the gate electrode;   a source electrode having a source contact portion electrically connected to the electron supply layer; and   a drain electrode having a drain contact portion electrically connected to the electron supply layer such that the drain contact portion and the source contact portion sandwich the gate electrode.   
     
     
         22 . The nitride semiconductor device according to  claim 21 , further comprising a wherein a cap layer made of a GaN layer formed on the electron transit layer. 
     
     
         23 . The nitride semiconductor device according to  claim 21 , wherein a thickness of the insulating layer at a portion penetrating the electron supply layer is thicker than a thickness of the other portions of the insulating layer. 
     
     
         24 . The nitride semiconductor device according to  claim 21 , wherein the first impurity layer further contains C (Carbon). 
     
     
         25 . The nitride semiconductor device according to  claim 21 , wherein a C (Carbon) concentration of the first impurity layer is less than a Zn concentration of the first impurity layer. 
     
     
         26 . The nitride semiconductor device according to  claim 21 , wherein a thickness of the first impurity layer is 0.5 μm to 5 μm. 
     
     
         27 . The nitride semiconductor device according to  claim 21 , wherein the Zn contained in the first impurity layer is partly contained in a region of the electron transit layer in a vicinity of the first impurity layer. 
     
     
         28 . The nitride semiconductor device according to  claim 21 , wherein the electron transit layer is a GaN layer and the electron supply layer is an AlN layer. 
     
     
         29 . The nitride semiconductor device according to  claim 21 , wherein
 the electron transit layer is a layer made of an Al 1-X Ga X N (0<X≤1) based material that is undoped, and   the electron supply layer is a layer made of an Al 1-X Ga X N (0<X≤1) based material differing in Al composition from the electron transit layer.   
     
     
         30 . The nitride semiconductor device according to  claim 21 , wherein
 the source electrode has a first lower layer in ohmic contact with the electron supply layer and a first upper layer laminated on the first lower layer, and   the drain electrode has a second lower layer in ohmic contact with the electron supply layer and a second upper layer laminated on the second lower layer.   
     
     
         31 . The nitride semiconductor device according to  claim 25 , wherein the Zn concentration of the first impurity layer is 5×10 17  cm −3  to 5×10 19  cm −3  and the first impurity layer contains C at a concentration of less than 5×10 17  cm −3 . 
     
     
         32 . The nitride semiconductor device according to  claim 21 , wherein the insulating layer is an SiN film. 
     
     
         33 . A nitride semiconductor device comprising:
 a first impurity layer made of an Al 1-X Ga X N (0<X≤1) based material and containing Zn as a first impurity;   an electron transit layer formed on the first impurity layer;   an electron supply layer formed on the electron transit layer;   a gate electrode formed over the electron transit layer;   a second impurity layer made of an Al 1-X Ga X N (0<X≤1) based material formed over the electron transit layer and containing a second impurity;   a nitride semiconductor layer that is undoped and is formed on the second impurity layer;   an insulating layer in contact with the undoped nitride semiconductor layer;   a source electrode having a source contact portion electrically connected to the electron supply layer; and   a drain electrode having a drain contact portion electrically connected to the electron supply layer such that the drain contact portion and the source contact portion sandwich the gate electrode.   
     
     
         34 . The nitride semiconductor device according to  claim 33 , further comprising: a mesa laminated portion having a wall surface extending over the undoped nitride semiconductor layer on the second impurity layer and the second impurity layer; and
 wherein the electron supply layer includes an extension portion extending in a direction intersecting a direction of lamination of the mesa laminated portion with respect to the mesa laminated portion and   the source electrode and the drain electrode are connected to the extension portion.   
     
     
         35 . The nitride semiconductor device according to  claim 33 , wherein the electron transit layer is a GaN layer and the electron supply layer is an AlN layer. 
     
     
         36 . The nitride semiconductor device according to  claim 33 , wherein
 the electron transit layer is a layer made of an Al 1-X Ga X N (0<X≤1) based material that is undoped, and   the electron supply layer is a layer made of an Al 1-X Ga X N (0<X≤1) based material differing in Al composition from the electron transit layer.