Semiconductor laser device
Disclosed herein is a semiconductor laser device utilizing a monocrystalline SiC substrate that is capable of assuring a sufficient heat dissipation property. The semiconductor laser device comprises: a monocrystalline SiC substrate having an electrical conductivity, the substrate having a first surface and a second surface; and a semiconductor laser chip (LD chip) arranged on the first surface. Also, the semiconductor laser device may comprise an insulating film arranged at a side of the first surface of the SiC substrate and configured to insulate a first electric conductive layer onto which the semiconductor laser chip is mounted and an electric conductive member (a second electric conductive layer and a heatsink portion) to be joined to a side of the second surface of the SiC substrate.
1. A semiconductor laser device, comprising:
a monocrystalline silicon carbide (SiC) substrate that is electrically conductive, the SiC substrate being provided with a first surface and a second surface; and
a semiconductor laser chip arranged on the first surface of the SiC substrate, wherein
the SiC substrate contains impurities equal to or greater than 1×10 14 /cm 3 ,
the SiC substrate contains less micropipes per a same unit of area than a monocrystalline SiC substrate that is not electrically conductive,
the SiC substrate further comprises:
a first electric conductive layer provided on the first surface of the SiC substrate;
a first joining layer made of AuSn and configured to join the first electric conductive layer to the semiconductor laser chip;
a second electric conductive layer provided on the second surface of the SiC substrate;
a second joining layer made of AuSn and configured to join the second electric conductive layer to a heatsink; and
an insulating film having a thickness less than 10 μm and configured to insulate the semiconductor laser chip from the heatsink,
the insulating film is formed on at least one of the first surface or the second surface of the SiC substrate along a direction of either the first surface or the second surface, and
the insulating film has a linear expansion coefficient between linear expansion coefficients of the SiC substrate and a semiconductor layer constituting the semiconductor laser chip.
2. The semiconductor laser device according to claim 1 , wherein
the insulating film insulates the first electric conductive layer from the second electric conductive layer.
3. The semiconductor laser device according to claim 1 , wherein the insulating film is arranged on the first surface.
4. The semiconductor laser device according to claim 1 , wherein the insulating film is arranged on the second surface.
5. The semiconductor laser device according to claim 1 , wherein the insulating film has a film thickness equal to or greater than 0.2 μm and equal to or less than 10 μm.
6. The semiconductor laser device according to claim 5 , wherein the insulating film has the film thickness equal to or less than 0.4 μm.
7. The semiconductor laser device according to claim 1 , wherein
the semiconductor layer constituting the semiconductor laser chip includes a material made of any of GaAs-based material, InP-based material, and GaN-based material, and
the insulating film is made of one or more materials selected from a group consisting of aluminum nitride, silicon nitride, silicon oxide, aluminum oxide, aluminum oxynitride, titanium nitride, and silicon oxynitride.
8. The semiconductor laser device according to claim 1 , wherein
the insulating film is any one of a monocrystalline aluminum nitride film and a polycrystalline aluminum nitride film.
9. The semiconductor laser device according to claim 1 , wherein
the SiC substrate has a crystalline structure including a first crystalline plane and a second crystalline plane, the first crystalline plane having a normal line direction thereof on a first crystalline axis and the second crystalline plane having a normal line direction thereof on a second crystalline axis having a higher heat conductivity than the first crystalline axis, and
the first crystalline plane inclines with respect to the first surface of the SiC substrate.
10. The semiconductor laser device according to claim 1 , wherein
the semiconductor laser chip has a rated power output equal to or greater than 1 W.
11. The semiconductor laser device according to claim 1 , wherein
a number of micropipes per wafer of the monocrystalline SiC substrate having the electrical conductivity is equal to or less than 30/cm 2 .