EP0348540A1
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EP
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Process for the selective growth of GaAs
Assignee: International Business Machines Corp
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Filing: 1988-06-28
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Granted: —
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Expires: 2008-06-28
Abstract
Abstract The process is particularly useful in the fabrication of GaAs quantum well (QW) laser diodes. Starting point is a ridge-patterned (100)-substrate (21), the crystal orientation of the sidewalls, e.g., (411A)-oriented, being different from that of the horizontal top. The sidewall facets thus have a lower Ga incorporation rate. In a molecular beam epitaxy (MBE) system, the lower AlGaAs cladding layer (22) is first grown, followed by the high-temperature growth of the active GaAs QW (23). Due to diffusion and desorption processes, the GaAs thickness at the sidewalls (23E) is smaller than on the horizontal top (23R) of the ridge. During a short growth interrupt, the GaAs completely desorps from the sidewall facets. With the subsequent growth of the upper cladding layer (24), the QW becomes laterally embedded in higher bandgap material providing for lateral electric confinement.
Inventors
- 👤 Heinz Peter Meier
- 👤 Edward A. Van Gieson
- 👤 Willi Walter
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 21:48
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/20; H01S5/22; H01S5/227; H10; H10H; H10H20/00; H10H20/01; H10H20/011; H10H20/013; H01S5/223; H01S5/2232; H01S5/2234; H01S5/2235; H01S5/2237; H01S5/30; H01S5/32; H01S5/3202; H01S5/3203
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
243 words
Process for the selective growth of GaAs on a patterned substrate for use in semiconductor laser diode fabrication, the process comprising the steps of * patterning the surface of the substrate (21) to provide a ridge structure (21A) on which a semiconductor laser diode is to be grown, the side wall facets of the ridge structure having, due to a different crystal orientation, a lower Ga incorporation rate than that of the horizontal facets, and * depositing the layers (22, 23, 24) forming the semiconductor laser diode on the patterned substrate (21) in a molecular beam epitaxy (MBE) system at a temperature above 700° C as follows : - growth of an AlGaAs lower cladding layer (22) of a first conductivity type on all facets of the ridge structure, - growth of an active GaAs quantum well (23) until a layer thickness between 5 and 10 nm is obtained on the top horizontal plane (23R), the thickness on the sidewall facets, having a lower Ga incorporation rate (23E), being lower, - growth interrupt by stopping the Ga supply until complete desorption of the thin GaAs layer (23E) from the sidewall facets, - growth of an AlGaAs upper cladding layer (24) of a second conductivity type on all facets of the structure, whereby the active quantum well (23R), serving as cavity of the completed semiconductor laser diode, is laterally embedded within higher bandgap material (22, 24) that provides for lateral carrier and current confinement.
Claim 2
Dependent Claim
243 words
Process for the selective growth of GaAs on a patterned substrate for use in semiconductor laser diode fabrication, the process comprising the steps of * patterning the surface of the substrate (21) to provide a ridge structure (21A) on which a semiconductor laser diode is to be grown, the side wall facets of the ridge structure having, due to a different crystal orientation, a lower Ga incorporation rate than that of the horizontal facets, and * depositing the layers (22, 23, 24) forming the semiconductor laser diode on the patterned substrate (21) in a molecular beam epitaxy (MBE) system at a temperature above 700° C as follows : - growth of an AlGaAs lower cladding layer (22) of a first conductivity type on all facets of the ridge structure, - growth of an active GaAs quantum well (23) until a layer thickness between 5 and 10 nm is obtained on the top horizontal plane (23R), the thickness on the sidewall facets, having a lower Ga incorporation rate (23E), being lower, - growth interrupt by stopping the Ga supply until complete desorption of the thin GaAs layer (23E) from the sidewall facets, - growth of an AlGaAs upper cladding layer (24) of a second conductivity type on all facets of the structure, whereby the active quantum well (23R), serving as cavity of the completed semiconductor laser diode, is laterally embedded within higher bandgap material (22, 24) that provides for lateral carrier and current confinement.
Claim 3
Dependent Claim
27 words
Process as claimed in claim 1, wherein the substrate (21) consists of GaAs, the horizontal facets of the ridge being (100)-oriented whereas the sidewall facets are (m11A)-oriented.
Claim 4
Dependent Claim
12 words
Process as claimed in claim 2, wherein the sidewall facets are (411A)-oriented.
Claim 5
Dependent Claim
25 words
Process as claimed in claim 1, wherein the AlGaAs composition of the lower and upper cladding layers (22, 24) is Al 0.4 Ga 0.6 As.
Claim 6
Dependent Claim
29 words
Process as claimed in claim 4, wherein the lower and upper cladding layers (22, 24) include, adjacent the embedded quantum well (23R), a waveguide layer with a graded Al-content.
Claim 7
Dependent Claim
44 words
Process as claimed in claim 5, wherein the AlGaAs composition within the waveguide layers varies from Al 0.18 Ga 0.82 As at the interface with the quantum well to Al 0.4 Ga 0.6 As at the transition to the bulk of the cladding layers.
Claim 8
Dependent Claim
30 words
Process as claimed in claim 1, wherein the temperature at which the layers (22, 23, 24) forming the laser diode are grown in the MBE system is about 720° C.
Claim 9
Dependent Claim
22 words
Process as claimed in claim 1, wherein the thickness of the lower and upper cladding layers (22, 24) is about 1.5 µm.
Claim 10
Dependent Claim
16 words
Process as claimed in claim 1, wherein the growth interrupt takes place for about 1 minute.
Claim 11
Dependent Claim
182 words
Semiconductor quantum well (QW) diode laser (20) having the QW (23R) embedded in higher bandgap material (22, 24) providing for lateral electric confinement, characterized in that - the laser comprises a layered structure (22, 23, 24) including the active GaAs QW layer (23R) sandwiched inbetween lower and upper AlGaAs cladding layers (22, 24), the material of the latter having a higher bandgap than that of the the active QW layer (23R), - the layers of said layered structure are deposited on a ridge (21A) of a patterned substrate surface, the sidewall facets of said ridge having, due to a different crystal orientation, a lower Ga incorporation rate than that of the horizontal facets, and in that - the active QW layer (23R) is selectively deposited on the horizontal section of the lower cladding layer (22) whereas the side wall section of the lower cladding layer is free of any deposited active layer material and thus in direct contact with the upper cladding layer (24), whereby the active QW layer (23R) is completely embedded within the higher bandgap cladding layer material (22, 24).
Claim 12
Dependent Claim
182 words
Semiconductor quantum well (QW) diode laser (20) having the QW (23R) embedded in higher bandgap material (22, 24) providing for lateral electric confinement, characterized in that - the laser comprises a layered structure (22, 23, 24) including the active GaAs QW layer (23R) sandwiched inbetween lower and upper AlGaAs cladding layers (22, 24), the material of the latter having a higher bandgap than that of the the active QW layer (23R), - the layers of said layered structure are deposited on a ridge (21A) of a patterned substrate surface, the sidewall facets of said ridge having, due to a different crystal orientation, a lower Ga incorporation rate than that of the horizontal facets, and in that - the active QW layer (23R) is selectively deposited on the horizontal section of the lower cladding layer (22) whereas the side wall section of the lower cladding layer is free of any deposited active layer material and thus in direct contact with the upper cladding layer (24), whereby the active QW layer (23R) is completely embedded within the higher bandgap cladding layer material (22, 24).
Claim 13
Dependent Claim
31 words
A Diode laser as claimed in claim 10, wherein the lower and upper cladding layers (22, 24) include, adjacent the embedded quantum well (23R), a waveguide layer with a graded Al-content.
References Cited (Backward Citations)
EP0190737A2
Cited
WO1987000694A1
Cited
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