Migration enhanced epitaxy fabrication of active regions having quantum wells
First Claim
1. A method for forming an active region associated with a semiconductor laser, the method comprising:
- forming a flattening layer by;
at a first flux of a group V constituent, growing from about 10 to about 73 nitrogen-free monolayers of group III and group V constituents by alternately depositing single atomic layers of group III constituents and group V constituents in the absence of nitrogen; and
at a second group V flux that is increased with respect to the first group V flux, growing one or more additional monolayers of alternating group III and group V constituents;
forming a quantum well over the flattening layer at a flux that is greater than the first flux, wherein at least a portion of the quantum well layers contain nitrogen; and
forming a cap layer over the quantum well, the cap layer being substantially free of at least one of In or N and wherein the cap layer is not grown by migration enhanced epitaxy.
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Accused Products
Abstract
Methods and systems produce flattening layers associated with nitrogen-containing quantum wells and prevent 3-D growth of nitrogen containing layers using controlled group V fluxes and temperatures. MEE (Migration Enhanced Epitaxy) is used to form a flattening layer upon which a quantum well is formed and thereby enhance smoothness of quantum well interfaces and to achieve narrowing of the spectrum of light emitted from nitrogen containing quantum wells. MEE is performed by alternately depositing single atomic layers of group III and V materials at a given group V flux and then raising the group V flux to saturate the surface of the flattening layer with the group V material. A cap layer is also formed over the quantum well. Where nitrogen is used, the systems incorporate a mechanical means of preventing nitrogen from entering the MBE processing chamber, such as a gate valve.
119 Citations
19 Claims
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1. A method for forming an active region associated with a semiconductor laser, the method comprising:
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forming a flattening layer by; at a first flux of a group V constituent, growing from about 10 to about 73 nitrogen-free monolayers of group III and group V constituents by alternately depositing single atomic layers of group III constituents and group V constituents in the absence of nitrogen; and at a second group V flux that is increased with respect to the first group V flux, growing one or more additional monolayers of alternating group III and group V constituents; forming a quantum well over the flattening layer at a flux that is greater than the first flux, wherein at least a portion of the quantum well layers contain nitrogen; and forming a cap layer over the quantum well, the cap layer being substantially free of at least one of In or N and wherein the cap layer is not grown by migration enhanced epitaxy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for forming a semiconductor laser, the method comprising the acts of:
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providing a substrate; developing a first confining region above the substrate; above the first confining region and at a temperature of from about 400°
C. to about 515°
C., developing an active region including at least one nitrogen-containing quantum well layer grown on a nitrogen-free flattening layer, wherein developing the nitrogen-free flattening layer comprises;using MEE, developing a first section of the flattening layer by alternately depositing single atomic layers of Ga and As without nitrogen being present, wherein depositing the single atomic layers of As is performed at a first As flux; and using MEE, developing a second section of the flattening layer at a second As flux that is higher than the first As flux to saturate the surface of the flattening layer with As such that the flattening layer is substantially flat and useful as a basis for growing at least one nitrogen-containing quantum well layer; and developing a second confining region above the active region. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification