Laser device with non-absorbing mirror, and method
A laser device with one or more active regions, such as quantum wells, gain/lighting media, or other devices, and one or more non-absorbing regions, may be formed by a first growth run (growing a first semiconductor layer), then performing selective, shallow-depth etching, and then a second growth run (growing a second semiconductor layer). The laser device may include a first portion, one or more active regions located on the first portion, and a second portion located on the active region(s). A third portion may be located on one or more ends of the first portion and on the second portion. The third portion may be formed during the second growth run, after the etching step. The non-absorbing region(s) may be formed by the third portion and the end(s) of the first portion. If desired, the non-absorbing region(s) may be produced without annealing or locally-induced quantum well intermixing.
1. A method of making an edge-emitting laser device, comprising:
epitaxially growing first, second, and third preform layers on a substrate;
subsequently, removing parts of the second and third preform layers by etching the second and third preform layers to form an etched region, and thereby forming one or more active regions from the second preform layer, defining an end of the one or more active regions, and leaving a layer of semiconductor material on the one or more active regions; and
subsequently, causing epitaxial growth in the etched region to form a non-absorbing region, and on the layer of semiconductor material, and wherein the epitaxial growths in the etched region and on the layer of semiconductor material occur simultaneously.
2. The method of claim 1 , wherein the one or more active regions of the laser device made by the method are located on a first portion, wherein material for the first portion and the one or more active regions is formed during a first growth run; wherein another portion of the laser device, located on an end portion of the first portion, is formed during a second growth run; and wherein the non-absorbing region is formed by the other portion.
3. The method of claim 2 , wherein the laser device made by the method includes a second portion located on the one or more active regions, wherein material for the second portion is formed during the first growth run, wherein the other portion is a third portion, wherein the first portion includes n-type semiconductor material, and wherein the second and third portions include p-type semiconductor material.
4. The method of claim 3 , wherein the one or more active regions has an etched end, the first portion and the third portion define a facet, and the non-absorbing region is located between the etched end and the facet.
5. The method of claim 4 , wherein the laser device made by the method includes a substrate, and wherein the first portion is located on the substrate.
6. The method of claim 5 , wherein the laser device made by the method includes first and second ohmic contacts, wherein the substrate is located on the second ohmic contact, and wherein the first portion, the one or more active regions, and the second and third portions are located between the first and second ohmic contacts.
7. The method of claim 2 , wherein the non-absorbing region of the laser device made by the method includes a first material, the one or more active regions includes a second material, and the first material has a larger band-gap than the second material, such that light generated by the laser device is not absorbed by the region, to thereby avoid catastrophic damage.
8. The method of claim 7 , wherein the non-absorbing region has a length in a direction of light emission, and wherein the length of the non-absorbing region is not greater than 500 μm.
9. The method of claim 8 , wherein the non-absorbing region is formed at an end of the laser device, wherein the laser device further includes a second non-absorbing region, and wherein the second non-absorbing region is formed during the second growth run.
10. The method of claim 1 , wherein the first preform layer is formed of n-type semiconductor material, the third preform layer is formed of a type of semiconductor material, which may be p-type or n-type semiconductor material, and the epitaxial growths in the etched region and on the layer of semiconductor material include deposition of the same type of semiconductor material.
11. The method of claim 10 , further comprising locating the first preform layer on a substrate, providing an ohmic contact on a first side of the device and connected to the substrate, and providing an ohmic contact on a second side of the device after causing the epitaxial growth on the layer of semiconductor material.
12. The method of claim 11 , further comprising forming a facet from the first preform layer and the epitaxial growth in the etched region.
13. The method of claim 12 , further comprising forming a second etched region, and thereby defining a second end of the one or more active regions, and causing epitaxial growth in the second etched region to form a second non-absorbing region.
14. A method of making an edge-emitting laser device, comprising:
growing a first semiconductor layer;
subsequently, selectively etching material grown during the growing of the first semiconductor layer; and
subsequently, growing a second semiconductor layer;
wherein the growing of the first semiconductor layer includes depositing a layer of n-type semiconductor material on a substrate, subsequently depositing a preform layer on the n-type semiconductor material, and subsequently depositing a first layer of p-type semiconductor material on the preform layer;
wherein the etching includes removing ends of the first layer of p-type semiconductor material and ends of the preform layer, without removing all of the first layer of p-type semiconductor material, and without removing all of the preform layer, to thereby form etched regions, and to thereby define one or more active regions between the etched regions; and
wherein the growing of the second semiconductor layer includes depositing a second layer of p-type semiconductor material in the etched regions, on etched surfaces of the layer of n-type semiconductor material, and on the first layer of p-type semiconductor material, to thereby form non-absorbing regions at opposite ends of the one or more active regions, and wherein the second layer of p-type semiconductor material is deposited simultaneously in the etched regions and on the first layer of p-type semiconductor material.
15. The method of claim 14 , further comprising providing ohmic contacts on opposite sides of the edge-emitting laser device.
16. The method of claim 15 , wherein the growing of the first semiconductor layer includes depositing a cap layer on the first layer of p-type semiconductor material, wherein ends of the cap layer are removed during the etching, and wherein a remaining portion of the cap layer is subsequently removed.
17. The method of claim 16 , wherein a lithography mask is used during the etching.
18. The method of claim 17 , further comprising forming facets at ends of the laser device, wherein the facets are formed from the layer of n-type semiconductor material and the second layer of p-type semiconductor material.
19. The method of claim 18 wherein the non-absorbing regions include regions where light generated by the laser device is not absorbed, to thereby avoid catastrophic damage, and wherein each one of the non-absorbing regions has a length not greater than 500 μm in a direction of laser emission.