Defect-free semiconductor templates for epitaxial growth and method of making same
AssigneeNSC-Nanosemiconductor GmbH
InventorsVitaly Shchukin, Nikolai Ledentsov
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Abstract
A method for fabrication of defect-free epitaxial layers on top of a surface of a first defect-containing solid state material includes the steps of selective deposition of a second material, having a high temperature stability, on defect-free regions of the first solid state material, followed by subsequent evaporation of the regions in the vicinity of the defects, and subsequent overgrowth by a third material forming a defect-free layer.
Claims82
A method for fabrication of defect-free epitaxial layers on top of a surface of a first solid state material having a first thermal evaporation rate and a plurality of defects, wherein the surface comprises at least one defect-free surface region, and at least one surface region in a vicinity of the defects, comprising the steps of:
- a) depositing a cap layer comprising a second material having a second thermal evaporation rate different from the first thermal evaporation rate, wherein the cap layer is selectively deposited on the defect-free surface regions, such that at least one of the surface regions in the vicinity of the defects remains uncovered;
- b) annealing a structure created in step a) at a temperature and duration such that at least one of the surface regions in the vicinity of the defects that is uncovered evaporates, while defect-free surface regions covered by the cap layer remain unaffected, and at least one annealed region is formed;
- and
- c) depositing a third material, lattice-matched or nearly lattice matched to the first solid state material, such that the third material overgrows both the cap layer and annealed regions of the first solid state material, forming a defect-free epitaxial layer.
A method for fabricating defect-free templates suitable for further epitaxial growth, wherein the defect-free templates are lattice-mismatched to a substrate, comprising the steps of:
- a) depositing a first epitaxial layer having a first thermal evaporation rate, wherein the first epitaxial layer is lattice-mismatched to the substrate, wherein a thickness of the first epitaxial layer exceeds a critical thickness required for a formation of defects, such that a plurality of defects are formed in the first epitaxial layer, such that a surface of said first epitaxial layer comprises at least one defect-free surface region, and at least one surface region in a vicinity of the defects;
- b) depositing a cap layer of a second material having a second thermal evaporation rate different from the first thermal evaporation rate, such that the cap layer is selectively deposited on the defect-free surface regions, and at least one of the surface regions in the vicinity of the defects remains uncovered;
- c) annealing a structure formed in step b) at a temperature and duration such that at least one of the surface regions in the vicinity of the defects that is uncovered evaporates, while defect-free surface regions covered by the cap layer remain unaffected, and at least one annealed region is formed;
- and
- d) depositing a third material, lattice-matched or nearly lattice matched to the first epitaxial layer, such that the third material overgrows both the cap layer and annealed regions of the first epitaxial layer, forming a defect-free epitaxial layer suitable as a template for further epitaxial growth.
The method of claim the vertical cavity surface emitting laser further comprises:
- e) an n-contact located directly below the substrate;
- and
- f) a p-contact located directly above the top mirror.
Dependencies are inferred from the claim text.