Semiconductor laser device

Abstract

A semiconductor laser device comprises a base, a first conductive layer, a second conductive layer, a third conductive layer, and a semiconductor laser chip in this order, each of which has a respective emitting-side end portion. The emitting-side end portion of the first conductive layer is in a common plane with the emitting-side end portion of the base. A thickness of the second conductive layer is greater than a thickness of the first conductive layer. The emitting-side end portion of the second conductive layer is disposed inward of the emitting-end portion of the first conductive layer. The emitting-side end portion of the third conductive layer is in a common plane with the emitting-side end portion of the second conductive layer. The emitting-side end portion of the semiconductor laser chip is disposed outward of the emitting-side end portion of the third conductive layer.

What is claimed is: 
     
         1 . A semiconductor laser device comprising:
 a base, a first conductive layer, a second conductive layer, a third conductive layer, and a semiconductor laser chip in this order, each of which has a respective emitting-side end portion,   wherein the emitting-side end portion of the first conductive layer is in a common plane with the emitting-side end portion of the base,   wherein the first conductive layer has an external connection region,   wherein the second conductive layer is formed in a different region from the external connection region of the first conductive layer,   wherein a thickness of the second conductive layer is greater than a thickness of the first conductive layer,   wherein the emitting-side end portion of the second conductive layer is disposed inward of the emitting-end portion of the first conductive layer,   wherein the emitting-side end portion of the third conductive layer is in a common plane with the emitting-side end portion of the second conductive layer, and   wherein the emitting-side end portion of the semiconductor laser chip is disposed outward of the emitting-side end portion of the third conductive layer.   
     
     
         2 . The semiconductor laser device according to  claim 1 , wherein the semiconductor laser chip includes a substrate and a semiconductor structure disposed on the substrate, and the third conductive layer is connected to the semiconductor laser chip at a semiconductor structure side of the semiconductor laser chip. 
     
     
         3 . The semiconductor laser device according to  claim 1 , wherein the second conductive layer has a higher thermal conductivity than the base. 
     
     
         4 . The semiconductor laser device according to  claim 1 , wherein the second conductive layer has a greater thickness than the third conductive layer. 
     
     
         5 . The semiconductor laser device according to  claim 1 , wherein the base is made of an insulating material. 
     
     
         6 . The semiconductor laser device according to  claim 2 , wherein the base is made of an insulating material. 
     
     
         7 . The semiconductor laser device according to  claim 5 , wherein the base is made of aluminum nitride. 
     
     
         8 . The semiconductor laser device according to  claim 6 , wherein the base is made of aluminum nitride. 
     
     
         9 . The semiconductor laser device according to  claim 1 , wherein the first conductive layer has a thickness of 0.5 μm or greater and 1.5 μm or less. 
     
     
         10 . The semiconductor laser device according to  claim 2 , wherein the first conductive layer has a thickness of 0.5 μm or greater and 1.5 μm or less. 
     
     
         11 . The semiconductor laser device according to  claim 1 , wherein the second conductive layer has a thickness of 4 μm or greater and 20 μm or less. 
     
     
         12 . The semiconductor laser device according to  claim 2 , wherein the second conductive layer has a thickness of 4 μm or greater and 20 μm or less. 
     
     
         13 . The semiconductor laser device according to  claim 1 , wherein the third conductive layer has a thickness of 2 μm or greater and 5 μm or less. 
     
     
         14 . The semiconductor laser device according to  claim 2 , wherein the third conductive layer has a thickness of 2 μm or greater and 5 μm or less. 
     
     
         15 . The semiconductor laser device according to  claim 1 , wherein the semiconductor laser chip comprises a GaN substrate and a plurality of semiconductor layers. 
     
     
         16 . The semiconductor laser device according to  claim 2 , wherein the semiconductor laser chip comprises a GaN substrate and a plurality of semiconductor layers. 
     
     
         17 . The semiconductor laser device according to  claim 2  further comprising a stem, a heat sink, and lead terminals, wherein the base is disposed on the heat sink arranged on the stem, the lead terminals are electrically connected to the semiconductor laser chip, and the lead terminals are disposed so as to penetrate the stem. 
     
     
         18 . The semiconductor laser device according to  claim 17 , wherein the heat sink is made of a metal material having higher heat dissipation than the stem. 
     
     
         19 . The semiconductor laser device according to  claim 17 , wherein the heat sink comprises copper. 
     
     
         20 . The semiconductor laser device according to  claim 17 , wherein the stem comprises iron. 
     
     
         21 . The semiconductor laser device according to  claim 1 , wherein the third conductive layer comprises a brazing material. 
     
     
         22 . The semiconductor laser device according to  claim 1 , wherein the third conductive layer comprises an AuSn solder. 
     
     
         23 . The semiconductor laser device according to  claim 1 , wherein the second conductive layer comprises at least one of gold, copper, and silver. 
     
     
         24 . The semiconductor laser device according to  claim 1 , wherein the third conductive layer comprises a brazing material, and the second conductive layer comprises at least one of gold, copper, and silver.