Semiconductor structure having a group iii-v semiconductor layer comprising a hexagonal mesh crystalline structure

Abstract

A semiconductor structure (100) comprising:a substrate (102),a first layer (106) of AlXGaYIn(1-X-Y)N disposed on the substrate,stacks (107, 109) of several second and third layers (108, 110) alternating against each other, between the substrate and the first layer,a fourth layer (112) of AlXGaYIn(1-X-Y)N, between the stacks,a relaxation layer of AlN disposed between the fourth layer and one of the stacks,and, in each of the stacks:the level of Ga of the second layers increases from one layer to the next in a direction from the substrate to the first layer,the level of Ga of the third layers is constant or decreasing from one layer to the next in said direction, the average mesh parameter of each group of adjacent second and third layers increasing from one group to the next in said direction,the thickness of the second and third layers is less than 5 nm.

1 . A semiconductor structure comprising at least:
 a substrate,   a first layer comprising GaN and arranged on the substrate,   a stack composed of several second and third layers arranged alternately on each other, located between the substrate and the first layer, and such that a semiconductor of the second layers is Al X Ga (1-X) N with 0≤X<1 and a semiconductor of the third layers is GaN,   
       and in which:
 a material of the substrate comprises a lattice parameter different of that of GaN, 
 the ratio of Ga in the semiconductor of the second layers varies and increases from one second layer to the next along a direction from the substrate to the first layer, 
 the thickness of each of the second and third layers is less than about 2 nm. 
 
     
     
         2 . The semiconductor structure according to  claim 1 , wherein the thickness of the first layer is between about 100 nm and 5 μm. 
     
     
         3 . The semiconductor structure according to  claim 1 , wherein the total number of second and third layers is between about 150 and 2000. 
     
     
         4 . The semiconductor structure according to  claim 1 , wherein the ratio of Ga in the semiconductor of the second layer that is closest to the substrate is between about 0 and 0.2, and/or the ratio of Ga in the semiconductor of the second layer that is closest to the first layer is between about 0.6 and 1, and/or the ratio of Ga of the average composition of the second layer closest to the first layer and of the third layer closest to the first layer is higher than about 0.2. 
     
     
         5 . The semiconductor structure according to  claim 1 , also comprising a buffer layer comprising AlN and located between the substrate and the stack comprising the second and third layers. 
     
     
         6 . The semiconductor structure according to  claim 5 , in which the thickness of the buffer layer is between about 5 nm and 1 μm. 
     
     
         7 . The semiconductor structure according to  claim 1 , in which the thicknesses of the second layers are similar and/or the thicknesses of the third layers are similar. 
     
     
         8 . The semiconductor structure according to  claim 1 , in which the substrate comprises monocrystalline silicon. 
     
     
         9 . The semiconductor structure according to  claim 1 , in which the total thickness of the stack comprising the second and third layers is less than or equal to about 5 μm. 
     
     
         10 . The semiconductor structure according to  claim 1 , further comprising an additional layer including GaN and having a thickness lower than that of the first layer, and such that the first layer is arranged between the additional layer and the stack comprising the second and third layers. 
     
     
         11 . The semiconductor structure according to  claim 10 , further comprising a spacer layer comprising AlN and arranged such that the additional layer is arranged between the spacer layer and the first layer. 
     
     
         12 . The semiconductor structure according to  claim 11 , further comprising an AlGaN layer such that the spacer layer is arranged between the AlGaN layer and the additional layer. 
     
     
         13 . The semiconductor structure according to  claim 1 , further comprising a p doped GaN layer such that the first layer is arranged between the p doped GaN layer and the stack comprising the second and third layers. 
     
     
         14 . A semiconductor device comprising at least one semiconductor structure according to  claim 1  and an active zone comprising the first layer of the semiconductor structure or located on the first layer of the semiconductor structure. 
     
     
         15 . The semiconductor device according to  claim 14 , in which said semiconductor device comprises at least one of a light emitting diode including the active zone and a transistor including the active zone.