| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a semiconductor device that can eliminate the adverse effect due to impurity diffusion from a buffer layer to a carrier layer. <P>SOLUTION: A superlattice layer (a first region) 21 is disposed at the lowermost portion of a buffer layer 20, and a diffusion preventing lower layer 22, a diffusion preventing layer (a second region) 23, and a diffusion preventing upper layer 24 are sequentially formed on the superlattice layer 21. In the buffer layer 20 and a carrier layer 30 that are formed on a substrate 11, an impurity is intentionally doped only in the superlattice layer 21 in the buffer layer 20, and the other layers are non-doped. The direction of the c-axis is the film thickness direction of each layer, and the direction of the a-axis is the in-plane direction (the direction perpendicular to the film thickness direction) of a growth layer. The a-axis lattice constant is substantially constant over the film thickness direction, whereas the c-axis lattice constant takes the maximum value in the diffusion preventing layer 23. <P>COPYRIGHT: (C)2012,JPO&INPIT |
