Epitaxial layer structure grown on graded substrate and method of growing the same
AssigneeNEC Corporation
InventorTakashi Matsumoto
Life of this patent
Estimating the term…
Abstract
An intentional lattice mismatch, .DELTA.a/a where .DELTA.a is a difference in the lattice constant of a constant-composition layer and an epitaxial layer and a is the lattice constant of the constant-composition layer, is introduced into the epitaxial layer of a crystal structure having a graded composition layer sandwiched between a single crystal bulk substrate and the constant composition layer so as to alleviate strain resulting from a lattice constant variation in the graded substrate.
Claims7
A crystal structure comprising:
- a single crystal bulk substrate having a first lattice constant,
- a graded-composition layer formed on said bulk substrate,
- a constant-composition layer formed on said graded-composition layer, said graded-composition layer and said constant composition layer having a second lattice constant which is different from said first lattice constant, and
- an epitaxial layer grown on said constant-composition layer with an intentional lattice mismatch .DELTA.a/a therebetween (wherein .DELTA.a is a difference in the lattice constant between said constant-composition layer and said epitaxial layer, and a is the lattice constant of said constant-composition layer), the value of .DELTA.a/a being in the range of 1.times.10.sup.-3 to 5.times.10.sup.-3 so as to alleviate a strain stored in said graded-composition layer and constant-composition layer due to the difference of said first and second lattice constants.
A crystal structure comprising:
- a single crystal bulk substrate selected from the group consisting of GaAs, GaP and InP,
- a graded-composition layer formed on said bulk substrate, said graded-composition layer being selected from the group consisting of GaAsP and InAsP,
- a constant-composition layer formed on said graded-composition layer, said constant-composition layer being selected from the group consisting of GaAsP and InAsP, and
- an epitaxial layer grown on said constant-composition layer with an intentional lattice mismatch .DELTA.a/a therebetween (wherein .DELTA.a is a difference in the lattice constant between said constant-composition layer and said epitaxial layer, and a is the lattice constant of said constant-composition layer), the value of .DELTA.a/a being in the range of 1.times.10.sup.-3 to 5.times.10.sup.-3 so as to alleviate a strain stored in said graded-composition layer and constant-composition layer, said epitaxial layer being selected from the group consisting of GaAlAs, InGaAsP, InGaAlAsP, ZnCdSSe and InGaP.
A crystal structure comprising:
- a graded substrate having a graded-composition layer sandwiched between a single crystal bulk substrate and a constant-composition layer, said graded substrate inherently storing a strain due to a difference in the lattice constant between said single crystal bulk substrate and both of said graded-composition layer and constant-composition layer, and
- an epitaxial layer grown on said constant-composition layer with an intentional lattice mismatch .DELTA.a/a therebeween (wherein .DELTA.a is a difference in the lattice constant between said constant-composition layer and said epitaxial layer, and a is the lattice constant of said constant-composition layer), the value of .DELTA.a/a being in the range of 3.times.10.sup.-3 to 5.times.10.sup.-3 so as to alleviate said strain stored in said graded substrate.
In a crystal structure comprising an epitaxial layer grown on a graded substrate having a graded-composition layer sandwiched between a single crystal bulk substrate and a constant-composition layer, the improvement in that an intentional lattice mismatch .DELTA.a/a of about 1.times.10.sup.-3 to 5.times.10.sup.-3 (wherein .DELTA.a is a difference in the lattice constant between said constant-composition layer and said epitaxial layer, and a is the lattice constant of said constant-composition layer) is introduced into said epitaxial layer such that when the lattice constant in said graded-composition layer increases in the direction from said single crystal bulk substrate toward said constant-composition layer, the lattice constant of said epitaxial layer is larger than that of said constant-composition layer and when the lattice constant in said graded-composition layer decreases in the direction from said single crystal bulk substrate toward said constant-composition layer, the lattice constant of said epitaxial layer is smaller than that of said constant-composition layer.
Dependencies are inferred from the claim text.