Laser diode structure with blocking layer
The present invention provides a self-aligned laser structure that can be fabricated on a p-substrate and provides a means for limiting the leakage current thereby improving the overall efficiency of the structure. The waveguide laser structure comprises a first series of layers deposited in sequence upon a p-InP, p-GaAs or p-GaN substrate or other form of p-substrate, wherein these layers form the p-clad layer. An active layer is subsequently deposited upon this first series of layers. A blocking layer of insulating or semi-insulating material is deposited upon the active layer, wherein this blocking layer has a trench formed therein, wherein this semi-insulating layer or layers are epitaxially deposited. The blocking layer provides a means for limiting current flow therethrough, thereby reducing leakage current. Upon the blocking layer are deposited a second series of layers completing the laser structure, wherein this second series of layers form the n-clad layer. Since the n-clad layer contains more than one material, the structure provides lateral waveguiding. Upon the completion of the deposition of all of the layers, a positive electrode is formed on the bottom surface of the first series of layers and a negative electrode is formed on the top of the second series of layers.
1 . A semiconductor laser structure, based on p-substrate materials, said structure including a plurality of layers, each layer including one or more sublayers, said structure comprising:
a) a first layer forming a p-clad layer, said first layer having a bottom surface;
b) a second layer being an active layer deposited on the first layer;
c) a third layer being a blocking layer formed from an insulating or semi-insulating material, said blocking layer including two parts aligned with a gap therebetween, said gap and said blocking layer having dimensions selected to meet a desired response of the semiconductor laser structure, said blocking layer deposited on the active layer; and
d) a fourth layer forming a n-clad layer, said fourth layer having a top surface, said fourth layer deposited on the third layer;
wherein a negative electrode is formed on the top surface and a positive electrode is formed of the bottom surface.
2 . A semiconductor laser structure according to claim 1 , where said p-substrate material is a p-InP substrate material, wherein said n-clad layer and p-clad layer are compatible with an InP material system.
3 . A semiconductor laser structure according to claim 1 , where said p-substrate material is a p-GaAs substrate material, wherein the n-clad layer and the p-clad layer are compatible with a GaAs material system.
4 . A semiconductor laser structure according to claim 2 , wherein said third layer is a Fe:InP layer.
5 . A semiconductor laser structure according to claim 2 , wherein said third layer is a Fe:InGaAsP layer.
6 . A semiconductor laser structure according to claim 2 , wherein said third layer is a Fe:InGaAlAs layer.
7 . A semiconductor laser structure according to claim 3 , wherein said third layer is a Cr:GaAs layer.
8 . A semiconductor laser structure according to claim 2 wherein said third layer is formed from a material having properties similar to Fe:InP.
9 . A semiconductor laser structure according to claim 3 wherein said third layer is formed from a material having properties similar to Cr:GaAs.
10 . A semiconductor laser structure according to claim 1 wherein said third layer is formed from an implanted semiconductor material.
11 . A semiconductor laser structure according to claim 1 wherein said third layer is formed from a semiconductor material that oxidizes.
12 . A semiconductor laser structure according to claim 1 where one of the layers comprises a grating.
13 . A semiconductor laser structure, based on p-substrate materials, said structure including a plurality of layers, each layer including one or more sublayers, said structure comprising:
a) a first layer, said first layer comprising a p-InP substrate, said first layer having a bottom surface;
b) a second layer deposited on the first layer, said second layer being an active layer;
c) a third layer deposited on the second layer, said third layer being a blocking layer comprising an insulating or semi-insulating material, said third layer including two parts, aligned with a gap therebetween, said gap having dimensions selected to meet a required specific response of the structure;
d) a fourth layer deposited on the third layer, said fourth layer comprising a n-InGaAsP layer; and
e) a fifth layer deposited on the fourth layer, said fifth layer being a cladding layer comprising a n-InP layer and said fifth layer having a top surface;
wherein a negative electrode is formed on the top surface and a positive electrode is formed of the bottom surface.
14 . A semiconductor laser structure according to claim 13 , where said first layer further comprises a p-InP layer deposited on the n-InP substrate.
15 . A semiconductor laser structure according to claim 13 , where said fourth layer further comprises a n-InP layer deposited prior to the n-InGaAsP layer.
16 . A semiconductor laser structure according to claim 13 , where the fifth layer further comprises a n-InGaAs layer deposited on the top of the n-InP layer.
17 . A semiconductor laser structure according to claim 13 , wherein said second active layer contains a single quantum well structure.
18 . A semiconductor laser structure according to claim 13 , wherein said second active layer contains a multi-quantum well structure.
19 . A semiconductor laser structure according to claim 13 , wherein said third layer is a Fe:InP layer.
20 . A semiconductor laser structure according to claim 13 , wherein said third layer is a Fe:InGaAsP layer.
21 . A semiconductor laser structure according to claim 13 , wherein said third layer is a Fe:InGaAlAs layer.
22 . A semiconductor laser structure according to claim 13 wherein said third layer is formed from a material having properties similar to Fe:InP.
23 . A semiconductor laser structure according to claim 13 wherein said third layer is formed from an implanted semiconductor material.
24 . A semiconductor laser structure according to claim 13 wherein said third layer is formed from a semiconductor material that oxidizes.
25 . A semiconductor laser structure according to claim 13 where one of the layers comprises a grating.
26 . A semiconductor laser structure according to claim 1 , where said p-substrate material is a p-GaN substrate material, wherein the n-clad layer and the p-clad layer are compatible with a GaN material system.