Dopant diffusion blocking for optoelectronic devices using InAlAs or InGaAlAs

Abstract

A method for decreasing the diffusion of dopant atoms in the active region, as well as the interdiffusion of different types of dopant atoms among adjacent doped regions, of optoelectronic devices is disclosed. The method of the present invention employs a plurality of InAlAs and/or InGaAlAs layers to avoid the direct contact between the dopant atoms and the active region, and between the dopant atoms in adjacent blocking structures of optoelectronic devices. A semi-insulating buried ridge structure, as well as a ridge structure, in which the interdiffusion of different types of dopant atoms is suppressed are also disclosed.

What is claimed as new and desired to be protected by Letters Patent of the United States is:  
     
         1 . An optoelectronic device comprising: 
 a substrate of a first type conductivity; and    a mesa structure provided on said substrate, said mesa structure having a least two sides and including an active region, said active region further being bounded on at least one side by a dopant blocking layer, said dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs.    
     
     
         2 . The optoelectronic device of  claim 1  further comprising a first current blocking layer at two sides of said mesa structure, a second current blocking layer of a first type conductivity formed over said first current blocking layer, and a cladding layer of a second type conductivity formed over said mesa structure and said second blocking layer.  
     
     
         3 . The optoelectronic device of  claim 1  further comprising a plurality of current blocking layers formed over said second current blocking layer.  
     
     
         4 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer is situated on top of said active region.  
     
     
         5 . The optoelectronic device of  claim 1  further comprising a doped second cladding layer of a second type conductivity in contact with said dopant blocking layer.  
     
     
         6 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer is situated between each of said two sides of said mesa structure and said first current blocking layer.  
     
     
         7 . The optoelectronic device of  claim 1 , wherein said doped second cladding layer is doped with a p-type dopant.  
     
     
         8 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer is an epitaxially grown layer.  
     
     
         9 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer has a thickness in the range of about 300 to 800 Angstroms.  
     
     
         10 . The optoelectronic device of  claim 1 , wherein said active region includes a layer capable of emitting light.  
     
     
         11 . The optoelectronic device of  claim 1 , wherein said active region includes a layer capable of absorbing light.  
     
     
         12 . The optoelectronic device of  claim 1 , wherein said active region includes a layer capable of modulating light.  
     
     
         13 . The optoelectronic device of  claim 1 , wherein said active region includes a layer capable of amplifying light.  
     
     
         14 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer comprises at least one InAlAs layer.  
     
     
         15 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer comprises at least one InGaAlAs layer.  
     
     
         16 . The optoelectronic device of  claim 1 , wherein said dopant blocking layer comprises at least one layer of InAlAs and at least one layer of InGaAlAs.  
     
     
         17 . A semiconductor optical device comprising: 
 a substrate of a first type conductivity; and    a mesa structure provided on said substrate, said mesa structure having at least two sides and including a dopant blocking layer, said dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs, said dopant blocking layer being further formed between an active region and a doped second cladding layer of a second type conductivity.    
     
     
         18 . The semiconductor optical device of  claim 17  further comprising a first current blocking layer at two sides of said mesa structure, a second current blocking layer of a first type conductivity formed over said first current blocking layer, and a cladding layer of a second type conductivity over said mesa structure and said second blocking layer.  
     
     
         19 . The semiconductor optical device of  claim 18  further comprising a plurality of current blocking layers formed over said second current blocking layer.  
     
     
         20 . The semiconductor optical device of  claim 17 , wherein said doped second cladding layer is doped with a dopant selected from the group consisting of zinc, beryllium and magnesium.  
     
     
         21 . The semiconductor optical device of  claim 17 , wherein said dopant blocking layer is an epitaxially grown layer.  
     
     
         22 . The semiconductor optical device of  claim 17 , wherein said dopant blocking layer has a thickness in the range of about 300 to 800 Angstroms.  
     
     
         23 . The semiconductor optical device of  claim 17 , wherein said active region includes a layer capable of emitting light.  
     
     
         24 . The semiconductor optical device of  claim 17 , wherein said active region includes a layer capable of absorbing light.  
     
     
         25 . The semiconductor optical device of  claim 17 , wherein said active region includes a layer capable of modulating light.  
     
     
         26 . The semiconductor optical device of  claim 17 , wherein said active region includes a layer capable of amplifying light.  
     
     
         27 . The semiconductor optical device of  claim 17 , wherein said dopant blocking layer comprises at least one InAlAs layer.  
     
     
         28 . The semiconductor optical device of  claim 17 , wherein said dopant blocking layer comprises at least one InGaAlAs layer.  
     
     
         29 . The semiconductor optical device of  claim 17 , wherein said dopant blocking layer comprises at least one layer of InAlAs and at least one layer of InGaAlAs.  
     
     
         30 . A method for forming a semiconductor laser comprising the steps of: 
 forming a plurality of stacked layers over a substrate of a first type conductivity, at least one of said layers being an active region and at least another one of said layers being a dopant blocking layer, said dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs; and    etching said plurality of stacked layers and said substrate to form a mesa structure on said substrate.    
     
     
         31 . The method of  claim 30  further comprising the steps of forming a first current blocking layer at two sides of said mesa structure, forming a second current blocking layer of a first type conductivity over said first current blocking layer, and forming a cladding layer of a second type conductivity over said mesa and said second current blocking layer.  
     
     
         32 . The method of  claim 30 , wherein said first type conductivity is n-type and said second type conductivity is p-type.  
     
     
         33 . The method of  claim 30 , wherein said first type conductivity is p-type and said second type conductivity is n-type.  
     
     
         34 . The method of  claim 30  further comprising the step of forming a plurality of current blocking layers at said two sides of said mesa structure.  
     
     
         35 . The method of  claim 30 , wherein said dopant blocking layer suppresses the diffusion of dopants from a second cladding layer into said active region, said second cladding layer being formed on top of and in contact with said dopant blocking layer.  
     
     
         36 . The method of  claim 35 , wherein said second cladding layer is grown selectively by metal organic vapor phase epitaxy.  
     
     
         37 . The method of  claim 35 , wherein said second cladding layer is of a second type conductivity.  
     
     
         38 . The method of  claim 35  further comprising the step of doping said second cladding layer.  
     
     
         39 . The method of  claim 30 , wherein said dopant blocking layer is epitaxially grown.  
     
     
         40 . The method of  claim 30 , wherein said dopant blocking layer is grown selectively by metal organic vapor phase epitaxy.  
     
     
         41 . The method of  claim 30 , wherein said dopant blocking layer is grown to a thickness in the range of about 300 to 800 Angstroms.  
     
     
         42 . The method of  claim 30 , wherein said active region includes a layer capable of emitting light when excited.  
     
     
         43 . The method of  claim 30 , wherein said active region includes a layer capable of absorbing light.  
     
     
         44 . The method of  claim 30 , wherein said active region includes a layer capable of modulating light.  
     
     
         45 . The method of  claim 30 , wherein said active region includes a layer capable of amplifying light.  
     
     
         46 . The method of  claim 30 , wherein said dopant blocking layer comprises at least one InAlAs layer.  
     
     
         47 . The method of  claim 30 , wherein said dopant blocking layer comprises at least one InGaAlAs layer.  
     
     
         48 . The method of  claim 30 , wherein said dopant blocking layer comprises at least one layer of InAlAs and at least one layer of InGaAlAs.  
     
     
         49 . A semiconductor optical device comprising: 
 a substrate of a first type conductivity;    a mesa structure provided on said substrate, said mesa structure having two sides and including an active region; and    a first dopant blocking layer at two sides of said mesa structure, said dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs.    
     
     
         50 . The semiconductor optical device of  claim 49  further comprising a plurality of current blocking layers formed over said second current blocking layer.  
     
     
         51 . The semiconductor optical device of  claim 49 , wherein said first dopant blocking layer comprises at least one InAlAs layer.  
     
     
         52 . The semiconductor optical device of  claim 49 , wherein said firs dopant blocking layer comprises at least one InGaAlAs layer.  
     
     
         53 . The semiconductor optical device of  claim 49 , wherein said first dopant blocking layer is an epitaxially grown layer.  
     
     
         54 . The semiconductor optical device of  claim 49 , wherein said first dopant blocking layer has a thickness in the range of about 300 to 3000 Angstroms.  
     
     
         55 . The semiconductor optical device of  claim 49  further comprising a first current blocking layer formed over said first dopant blocking layer, a second current blocking layer of a first type conductivity formed over said first current blocking layer, and a cladding layer of a second type conductivity formed over said mesa structure and said second blocking layer.  
     
     
         56 . The semiconductor optical device of  claim 55 , wherein said first current blocking layer is doped.  
     
     
         57 . The semiconductor optical device of  claim 56 , wherein said dopant is a semi-insulating type dopant.  
     
     
         58 . The semiconductor optical device of  claim 57 , wherein said first current blocking layer is an InP(Fe) layer.  
     
     
         59 . The semiconductor optical device of  claim 55 , wherein said second current blocking layer is doped with a dopant selected from the group consisting of silicon, sulfur and tin.  
     
     
         60 . The semiconductor optical device of  claim 55 , wherein said mesa structure further comprises a second cladding layer formed over said active region.  
     
     
         61 . The semiconductor optical device of  claim 55 , wherein said mesa structure further comprises a second dopant blocking layer formed in between said second cladding layer and said active region.  
     
     
         62 . The semiconductor optical device of  claim 61 , wherein said second dopant blocking layer comprises a material selected from the group consisting of InAlAs and InGaAlAs.  
     
     
         63 . The semiconductor optical device of  claim 61 , wherein said second dopant blocking layer comprises at least one InAlAs layer.  
     
     
         64 . The semiconductor optical device of  claim 61 , wherein said second dopant blocking layer comprises at least one InGaAlAs layer.  
     
     
         65 . The semiconductor optical device of  claim 61 , wherein said second dopant blocking layer comprises at least one layer of InAlAs and at least one layer of InGaAlAs.  
     
     
         66 . The semiconductor optical device of  claim 49 , wherein said active region includes a layer capable of emitting light.  
     
     
         67 . The semiconductor optical device of  claim 49 , wherein said active region includes a layer capable of absorbing light.  
     
     
         68 . The semiconductor optical device of  claim 49 , wherein said active region includes a layer capable of modulating light.  
     
     
         69 . The semiconductor optical device of  claim 49 , wherein said active region includes a layer capable of amplifying light.  
     
     
         70 . A semiconductor optical device comprising: 
 a substrate of a first type conductivity;    a mesa structure provided on said substrate, said mesa structure having two sides and including an active region, said mesa structure further including a first dopant blocking layer in contact with said active region, said first dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs; and    a second dopant blocking layer at two sides of said mesa structure.    
     
     
         71 . The semiconductor optical device of  claim 70  further comprising a first current blocking layer formed over said second dopant blocking layer, a third dopant blocking layer formed over said first current blocking layer, and a cladding layer of a second type conductivity formed over said mesa structure and said third dopant blocking layer.  
     
     
         72 . The semiconductor optical device of  claim 71  further comprising a plurality of current blocking layers formed in between said first current blocking layer and said third dopant blocking layer.  
     
     
         73 . The semiconductor optical device of  claim 71 , wherein said second dopant blocking layer comprises a material selected from the group consisting of InAlAs and InGaAlAs.  
     
     
         74 . The semiconductor optical device of  claim 71 , wherein said third dopant blocking layer comprises a material selected from the group consisting of InAlAs and InGaAlAs.  
     
     
         75 . The semiconductor optical device of  claim 71 , wherein said first dopant blocking layer is situated on top of said active region.  
     
     
         76 . The semiconductor optical device of  claim 71  further comprising a doped second cladding layer of a second type conductivity in contact with said first and second dopant blocking layers.  
     
     
         77 . The semiconductor optical device of  claim 76 , wherein said doped second cladding layer is doped with a p-type dopant.  
     
     
         78 . The semiconductor optical device of  claim 71 , wherein said second dopant blocking layer has a thickness in the range of about 300 to 3000 Angstroms.  
     
     
         79 . The semiconductor optical device of  claim 71 , wherein said third dopant blocking layer has a thickness in the range of about 300 to 3000 Angstroms.  
     
     
         80 . The semiconductor optical device of  claim 70 , wherein said first dopant blocking layer has a thickness in the range of about 300 to 800 Angstroms.  
     
     
         81 . The semiconductor optical device of  claim 70 , wherein said active region includes a layer capable of emitting light when excited.  
     
     
         82 . The semiconductor optical device of  claim 70 , wherein said active region includes a layer capable of absorbing light.  
     
     
         83 . The semiconductor optical device of  claim 70 , wherein said active region includes a layer capable of modulating light.  
     
     
         84 . The semiconductor optical device of  claim 70 , wherein said active region includes a layer capable of amplifying light.  
     
     
         85 . A semiconductor optical device comprising: 
 a substrate of a first type conductivity;    a mesa structure provided on said substrate, said mesa structure having two sides and including an active region;    a first current blocking layer at two sides of said mesa structure;    a second current blocking layer of a first type conductivity formed over said first current blocking layer;    a first dopant blocking layer formed over said second current blocking layer, said first dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs; and    a cladding layer of a second type conductivity formed over said mesa structure and said first dopant blocking layer.    
     
     
         86 . The semiconductor optical device of  claim 85  further comprising a second dopant blocking layer on top of said active region.  
     
     
         87 . The semiconductor optical device of  claim 86 , wherein said second dopant blocking layer comprises a material selected from the group consisting of InAlAs and InGaAlAs.  
     
     
         88 . The semiconductor optical device of  claim 86 , wherein said second dopant blocking layer has a thickness in the range of about 300 to 800 Angstroms.  
     
     
         89 . The semiconductor optical device of  claim 85  further comprising a third dopant blocking layer between said two sides of said mesa stripe and said first current blocking layer.  
     
     
         90 . The semiconductor optical device of  claim 89 , wherein said third dopant blocking layer comprises a material selected from the group consisting of InAlAs and InGaAlAs.  
     
     
         91 . The semiconductor optical device of  claim 89 , wherein said third dopant blocking layer has a thickness in the range of about 300 to 3000 Angstroms.  
     
     
         92 . The semiconductor optical device of  claim 86  further comprising a doped first cladding layer of a second type conductivity in contact with said second dopant blocking layer.  
     
     
         93 . The semiconductor optical device of  claim 92 , wherein said doped second cladding layer is doped with a p-type dopant.  
     
     
         94 . The semiconductor optical device of  claim 85 , wherein said first dopant blocking layer has a thickness in the range of about 300 to 3000 Angstroms.  
     
     
         95 . An optoelectronic device comprising: 
 a substrate of a first type conductivity;    a mesa structure provided on said substrate, said mesa structure having two sides and including an active region, said active region further being bounded on at least one side by a dopant blocking layer, said dopant blocking layer comprising a material selected from the group consisting of InAlAs and InGaAlAs; and    an insulating layer at two sides of said mesa structure.    
     
     
         96 . The optoelectronic device of  claim 95 , wherein said mesa structure further includes a cladding layer of a second type conductivity formed over said mesa structure, and an ohmic contact layer formed over said cladding layer.  
     
     
         97 . The optoelectronic device of  claim 95 , wherein said dopant blocking layer is situated on top of said active region.  
     
     
         98 . The optoelectronic device of  claim 95  further comprising a doped second cladding layer of a second type conductivity in contact with said dopant blocking layer.  
     
     
         99 . The optoelectronic device of  claim 98 , wherein said doped second cladding layer is doped with a p-type dopant.  
     
     
         100 . The optoelectronic device of  claim 95 , wherein said dopant blocking layer is an epitaxially grown layer.  
     
     
         101 . The optoelectronic device of  claim 95 , wherein said dopant blocking layer has a thickness in the range of about 300 to 800 Angstroms.  
     
     
         102 . The optoelectronic device of  claim 95 , wherein said active region includes a layer capable of absorbing light.  
     
     
         103 . The optoelectronic device of  claim 95 , wherein said active region includes a layer capable of modulating light.  
     
     
         104 . The optoelectronic device of  claim 95 , wherein said insulating layer is formed of polyimide.