Semiconductor laser device and fabrication method therefor
View Patent ↗A semiconductor laser device has a multilayer structure including a first clad layer, an active layer, and a second clad layer stacked successively on a semiconductor substrate in order of increasing distance from the semiconductor substrate. At least one of the first clad layer and the second clad layer has a compressive distortion with respect to the semiconductor substrate. At least one of the first clad layer and the second clad layer includes a semiconductor layer having a tensile distortion with respect to the semiconductor substrate.
1. A semiconductor laser device, which has a self-sustained pulsation characteristic, comprising:
a lower clad layer formed on a semiconductor substrate;
an active layer formed on the lower clad layer;
a first upper clad layer formed on the active layer;
a semiconductor layer formed on the first upper clad layer; and
a second upper clad layer formed on the semiconductor layer, wherein:
the lower clad layer, the first upper clad layer and the second upper clad layer each made of AlGaInP have a positive lattice mismatch, which is in a range of 2.0×10 −4 to 3.0×10 −3 , inclusive, with respect to the semiconductor substrate,
the semiconductor layer has a negative lattice mismatch, which is in a range of −2.0×10 −3 to −2.0×10 −4 , inclusive, with respect to the semiconductor substrate,
impurity concentrations of the first and second upper clad layers are not less than 3×10 17 cm −3 ,
a well layer composing the active layer has the compressive distortion with respect to the semiconductor substrate and a film thickness of not less than 20 nm, and
the semiconductor layer is made of Ga x In y P (x>y) and functions as an etching stop layer when a ridge portion is formed in the second upper clad layer by etching.