Extended wavelength strained layer lasers having strain compensated layers
First Claim
1. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
- said substrate having a substrate lattice constant between 5.63 Å and
5.67 Å
;
a first strained layer having a lattice constant smaller than said substrate lattice constant and being disposed between said substrate and said active region;
said active region comprising one pseudomorphic light emitting active layer disposed above said substrate, said active layer comprising In, Ga and As, said active layer comprises at least two strained layers, and a third layer disposed between said two strained layers, said active layer having a thickness equal to or less than 80 Å
; and
wherein said light emitting device has an emission wavelength of at least 1.3 μ
m.
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Accused Products
Abstract
Several methods are used in novel ways with newly identified and viable parameters to decrease the peak transition energies of the pseudomorphic InGaAs/GaAs heterostructures. These techniques, taken separately or in combination, suffice to permit operation of light emitting devices at wavelengths of 1.3 μm or greater of light-emitting electro-optic devices. These methods or techniques, by example, include: (1) utilizing new superlattice structures having high In concentrations in the active region, (2) utilizing strain compensation to increase the usable layer thickness for quantum wells with appropriately high In concentrations, (3) utilizing appropriately small amounts of nitrogen (N) in the pseudomorphic InGaAsN/GaAs laser structure, and (4) use of nominal (111) oriented substrates to increase the usable layer thickness for quantum wells with appropriately high In concentrations. In all of the above techniques, gain offset may be utilized in VCSELs to detune the emission energy lower than the peak transition energy, by about 25 meV or even more, via appropriate DBR spacing. Gain offset may also be utilized in some forms of in-plane lasers. Increased temperature may also be used to decrease peak transition energy (and therefore the emission energy) by about 50 meV/100° C. All these techniques are furthermore applicable to other material systems, for example, extending the emission wavelength for laser diodes grown on InP substrates. Additionally, structures which utilize the above techniques are discussed.
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Citations
73 Claims
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1. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
-
said substrate having a substrate lattice constant between 5.63 Å and
5.67 Å
;a first strained layer having a lattice constant smaller than said substrate lattice constant and being disposed between said substrate and said active region; said active region comprising one pseudomorphic light emitting active layer disposed above said substrate, said active layer comprising In, Ga and As, said active layer comprises at least two strained layers, and a third layer disposed between said two strained layers, said active layer having a thickness equal to or less than 80 Å
; andwherein said light emitting device has an emission wavelength of at least 1.3 μ
m. - View Dependent Claims (2, 3, 4, 5)
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6. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
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said substrate having a substrate lattice constant between 5.63 Å and
5.67 Å
;a first strained layer having a lattice constant smaller than a substrate lattice constant and being disposed between said substrate and said active region; said active region comprising at least one pseudomorphic light emitting active layer disposed above said first strained layer, said active layer comprising In, Ga and As;
said active layer having a combined concentration of In and Sb of 25% or greater of a semiconductor material in said active layer, said active layer having a thickness greater than CT for a given material, where;
space="preserve" listing-type="equation">CT=(0.4374/f)(ln (CT/4)+1),where f is an average lattice mismatch of said active layer normalized to a lattice constant of 5.65 Å
;wherein said light emitting device has an emission wavelength of at least 1.3 μ
m. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
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said substrate having a substrate lattice constant between 5.63 Å and
5.67 Å
;a first strained layer disposed between said substrate and said active region, said first strained layer having a first accumulated strain and a first critical accumulated strain associated therewith, said first accumulated strain being less than said first critical accumulated strain; said active region comprising at least one pseudomorphic light emitting active layer disposed above said substrate, said active layer comprising In, Ga and As;
said active layer having a concentration of In and Sb greater than 25% of a semiconductor material in said active layer, said active layer having a second accumulated strain and a second critical accumulated strain associated therewith, the algebraic sum of said first and second accumulated strains being less than said second critical accumulated strain;wherein an algebraic sum said first and second critical accumulated strains for a given material equals a strain of said material multiplied by CT for a given material, where;
space="preserve" listing-type="equation">CT=(0.4374/f) ln (CT/4)+1!,where f is an average lattice mismatch of said active layer normalized to a lattice constant of 5.65 Å
;wherein said light emitting device has an emission wavelength of at least 1.3 μ
m. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
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said substrate comprising having a substrate lattice constant between 5.63 Å and
5.67 Å
;a first strained layer disposed between said substrate and said active region, said first strained layer having a first accumulated strain and a first critical accumulated strain associated therewith, said first accumulated strain being less than said first critical accumulated strain; said active region comprising at least one pseudomorphic light emitting active layer disposed above said substrate, said active layer comprising In and Ga, said active layer comprising at least two strained layers, and a third layer disposed between said two strained layers, said active layer having a second accumulated strain and a second critical accumulated strain associated therewith, the algebraic sum of said first and second accumulated strains being less than said second critical accumulated strain; and wherein said light emitting device has an emission wavelength of at least 1.3 μ
m. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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59. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
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said substrate comprising having a substrate lattice constant between 5.63 Å and
5.67 Å
;a first strained layer disposed between said substrate and said active region, said first strained layer having a first accumulated strain and a first critical accumulated strain associated therewith, said first accumulated strain being less than said first critical accumulated strain; said active region comprising at least one pseudomorphic light emitting active layer disposed above said substrate, said active layer comprising In, Ga and As, said active layer comprises at least two strained layers, and a third layer disposed between said two strained layers, forming a superlattice having an average sum of In and Sb concentrations in said superlattice at 25% or greater of a semiconductor material in said active layer, said active layer having a second accumulated strain and a second critical accumulated strain associated therewith, said second accumulated strain being less than said second critical accumulated strain; wherein said first and second critical accumulated strain for a given material equals a strain of said material multiplied by CT for a given material, where;
space="preserve" listing-type="equation">CT=(0.4374/f) ln (CT/4)+1!,where f is an average lattice mismatch of said active layer normalized to a lattice constant of 5.65 Å
; andwherein said light emitting device has an emission wavelength of at least 1.3 μ
m.
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60. A light emitting device having at least a substrate and an active region, said light emitting device comprising:
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said substrate comprising having a substrate lattice constant between 5.63 Å and
5.67 Å and
having a growth plane which has an orientation within 15°
of (111);said active region comprising at least one pseudomorphic light emitting active layer disposed above said substrate, said active layer comprising In, Ga and As, said active layer having a thickness equal to or less than twice a respective CT, where;
space="preserve" listing-type="equation">CT=(0.4374/f) ln (CT/4)+1!,where f is an average lattice mismatch of said active layer normalized to a lattice constant of 5.65 Å
;wherein said active layer has an average sum of In and Sb concentrations of equal to or greater than 25% or greater of a semiconductor material in said active layer; and wherein said light emitting device has an emission wavelength of at least 1.3 μ
m. - View Dependent Claims (61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73)
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Specification