Semiconductor device and method of producing the same

Abstract

To provide a semiconductor device including a functional laminate having flatness and crystallinity improved by effectively passing on the crystallinity and flatness improved in a buffer to the functional laminate, and to provide a method of producing the semiconductor device; in the semiconductor device including the buffer and the functional laminate having a plurality of nitride semiconductor layers, the functional laminate includes a first n-type or i-type Al x Ga 1-x N layer (0≦x<1) on the buffer side, and an Al z Ga 1-z N adjustment layer containing p-type impurity, which has an approximately equal Al composition to the first Al x Ga 1-x N layer (x−0.05≦z≦x+0.05, 0≦z<1) is provided between the buffer and the functional laminate.

1 . A semiconductor device comprising a buffer and a functional laminate including a plurality of nitride semiconductor layers, on a substrate,
 wherein the functional laminate includes a first n-type or i-type Al x Ga 1-x N layer (0≦x<1) on the buffer side, and   an Al z Ga 1-z N adjustment layer containing p-type impurity, which has an approximately equal Al composition to the first Al x Ga 1-x N layer (x−0.05≦z≦x+0.05, 0≦z<1) is provided between the buffer and the functional laminate.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein the substrate is an AlN template substrate. 
     
     
         3 . The semiconductor device according to  claim 1 , wherein the buffer includes an Al α Ga 1-α N layer (0≦α≦1) at least on the functional laminate side, and difference between an Al composition α of the Al α Ga 1-α N layer and an Al composition x of the first Al x Ga 1-x N layer is 0.1 or more. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein
 the first Al x Ga 1-x N layer is n-type, and   the functional laminate includes at least a light emitting layer and a second Al y Ga 1-y N layer (0≦y<1) in this order on the first Al x Ga 1-x N layer.   
     
     
         5 . The semiconductor device according to  claim 1 , wherein an i-type Al w Ga 1-w N layer (x−0.05≦w≦x+0.05, 0≦w<1) not doped with impurity is further provided between the Al z Ga 1-z N adjustment layer containing p-type impurity and the first Al x Ga 1-x N layer. 
     
     
         6 . The semiconductor device according to  claim 5 , wherein the Al z Ga 1-z N adjustment layer containing p-type impurity and the i-type Al w Ga 1-w N layer not doped with impurity satisfy the relationship of z<w. 
     
     
         7 . The semiconductor device according to  claim 1 , wherein a thickness of the Al z Ga 1-z N adjustment layer containing p-type impurity is in a range of 100 nm to 1500 nm. 
     
     
         8 . The semiconductor device according to  claim 1 , wherein the Al z Ga 1-z N adjustment layer containing p-type impurity is doped with Mg, and the Mg concentration is in a range of 5×10 16 /cm 3  to 2×10 20 /cm 3 . 
     
     
         9 . The semiconductor device according to  claim 1 , wherein a concentration of O contained in the first Al x Ga 1-x N layer is less than 2×10 18 /cm 3 . 
     
     
         10 . The semiconductor device according to  claim 1 , wherein the buffer includes a superlattice strain buffer layer having a superlattice structure formed by alternately stacking Al β Ga 1-β N layers (0≦β≦0.3) and AlN layers. 
     
     
         11 . A method of producing a semiconductor device, wherein a buffer, an Al z Ga 1-z N adjustment layer containing p-type impurity (x−0.05≦z≦x+0.05, 0≦z<1), and a functional laminate including an i-type or n-type Al x Ga 1-x N layer (0≦x<1) are sequentially formed on a substrate.