Mechanical stabilization of lattice mismatched quantum wells
View Patent ↗In order to achieve a long wavelength, 1.3 micron or above, VCSEL or other semiconductor laser, layers of strained quantum well material are supported by mechanical stabilizers which are nearly lattice matched with the GaAs substrate, or lattice mismatched in the opposite direction from the quantum well material; to allow the use of ordinary deposition materials and procedures. By interspersing thin, unstrained layers of e.g. gallium arsenide in the quantum well between the strained layers of e.g. InGaAs, the GaAs layers act as mechanical stabilizers keeping the InGaAs layers thin enough to prevent lattice relaxation of the InGaAs quantum well material. Through selection of the thickness and width of the mechanical stabilizers and strained quantum well layers in the quantum well, 1.3 micron and above wavelength lasing is achieved with use of high efficiency AlGaAs mirrors and standard gallium arsenide substrates.
1. A semiconductor laser comprising:
an active layer that includes at least one quantum well, the at least one quantum well including semiconductor alloy layers under mechanical stress and stabilizing material layers, wherein the stabilizing material layers are interspersed between the semiconductor alloy layers and serve as mechanical stabilizers for the semiconductor alloy layers;
barrier layers sandwiching the active layer; and
mirror layers disposed outside of the barrier layers.
2. The invention of claim 1 , wherein the semiconductor laser is one of a vertical cavity surface emitting laser, an edge emitting laser, or a light emitting diode.
3. The invention of claim 1 , wherein the semiconductor alloy layers are comprised of one of InGaAs, GaAsSb, or InGaAsSb, and the substrate is comprised of GaAs.
4. The invention of claim 3 , wherein the mirror layers are comprised of AlGaAs.
5. The invention of claim 4 , wherein the quantum wells are about 80 Å–250 Å thick.
6. The invention of claim 4 , wherein the quantum well mechanical stabilizer layers are about 9.5 Å–11.2 Å thick.
7. The invention of claim 4 , wherein the alloy layers are about 24 Å thick.
8. The invention of claim 1 , wherein the stabilizing layers are substantially unstrained.
9. A semiconductor laser, comprising:
a substrate; and
an active layer disposed above the substrate and comprising:
at least one quantum well that includes within it:
semiconductor alloy layers under mechanical stress; and
stabilizing material layers that are arranged in alternating fashion with
the semiconductor alloy layers, the stabilizing layers serving as mechanical stabilizers for the semiconductor alloy layers;
barrier layers sandwiching the active layer; and
mirror layers disposed outside of the barrier layers.
10. The semiconductor laser as recited in claim 9 , wherein the stabilizing layers are substantially lattice matched with the substrate.
11. The semiconductor laser as recited in claim 9 , wherein the semiconductor laser comprises one of: a vertical cavity surface emitting laser; an edge emitting laser; or a light emitting diode.
12. The semiconductor laser as recited in claim 9 , wherein the semiconductor alloy layers are comprised of one of InGaAs, GaAsSb, or InGaAsSb, and the substrate is comprised of GaAs.
13. The semiconductor laser as recited in claim 9 , wherein the stabilizing layers are substantially unstrained.