Semiconductor laser device and its manufacturing method, and optical disc reproducing and recording apparatus
View Patent ↗Immediately after stacking of a barrier layer formed of GaAsP of a multiple-strain quantum well active layer 105 at a growth temperature of 650° C., a second upper guide layer 126 formed of AlGaAs is stacked. This second upper guide layer 126 is grown while the temperature is kept at 650° C., which is a growth temperature suitable for P-based layers. By reducing the desorption of P from the barrier layer, the roughness level of the interface between the barrier layer and the second upper guide layer 126 is lowered to 20 Å or less. Thereafter, a first upper guide layer 106 is stacked. Growth temperature of this first upper guide layer 106 , which is 650° C. at a start of the growth, is started to be increased concurrently with the growth, and gradually elevated until an end of the growth so as to reach 750° C. at the end of the growth.
1. A method for manufacturing a semiconductor laser device including, on a GaAs substrate, at least a first-conductive-type lower cladding layer, a lower guide layer, a quantum well active layer composed of at least one well layer and at least two barrier layers, an upper guide layer and a second-conductive-type upper cladding layer, one on another, wherein
at least one layer out of the plurality of layers is a P-based layer formed of group III–V compound semiconductor containing P as a group V element, the method comprising the steps of:
subjecting the P-based layer to crystal growth at a first growth temperature; and
above the P-based layer, starting growth of an As-based layer formed of group III–V compound semiconductor containing not P but As as a group V element at a growth temperature approximately equal to the first growth temperature, and thereafter furthering the growth while elevating the temperature to a second growth temperature.
2. The method for manufacturing a semiconductor laser device according to claim 1 , further comprising the step of: before the growth of the As-based layer, making one layer or a plurality of layers of other As-based layer grown just above the P-based layer at a temperature approximately equal to the first growth temperature.
3. The method for manufacturing a semiconductor laser device according to claim 1 , wherein the first growth temperature is not less than 600° C. and not more than 680° C.
4. The method for manufacturing a semiconductor laser device according to claim 1 , wherein the second growth temperature is not less than 700° C. and not more than 780° C.
5. The method for manufacturing a semiconductor laser device according to claim 1 , wherein the P-based layer is formed of InGaAsP, InGaP, GaAsP or AlGaInP.
6. The semiconductor laser device according to claim 1 , wherein the As-based layer is formed of GaAs, AlGaAs, AlAs, InGaAs or AlGaInAs.