Method for production of a semiconductor laser

Claim 1

A method of producing a semiconductor laser device capable of oscillation in a self-pulsation mode, said method comprising the steps of: growing a lower cladding layer, an active layer and an upper cladding layer on a semiconductive substrate, the cladding layers and the active layer all being of AlGaAs with the aluminum molar proportion of the active layer being lower than that of the cladding layers, the cladding layers being of opposite conductivity types thereby to form a p-n junction at the active layer; etching the upper cladding layer to form a central mesa separated by comparatively thin sections of the upper cladding layer, the thin sections being of sufficient thinness to be readily gauged by optical interferometrical techniques; using MOCVD techniques to grow a buffer layer over the thin etched portions of the upper cladding layer of predetermined thickness, the buffer layer being of AlGaAs and having an aluminum content which is substantially the same as that of the upper cladding layer such that said buffer layer and upper cladding layer function as a composite layer having a combined refractive index mismatched with that of the active layer; growing a current blocking layer over the buffer layer, and forming a contact layer and electrodes to produce a completed semiconductor device having a p-n junction at the active layer so that when said device is energized carriers are injected into the active layer in the region defined by the mesa; the thickness of the composite cladding and buffer layers being coordinated to the width of the mesa to produce a sufficiently thick composite layer for causing said laser when energized to function in the self-pulsation mode.

Claim 2

A method of producing a semiconductor laser device capable of oscillation in a self-pulsation mode, said method comprising the steps of: growing a lower cladding layer, an active layer and an upper cladding layer on a semiconductive substrate, the cladding layers and the active layer all being of AlGaAs with the aluminum molar proportion of the active layer being lower than that of the cladding layers, the cladding layers being of opposite conductivity types thereby to form a p-n junction at the active layer; etching the upper cladding layer to form a central mesa separated by comparatively thin sections of the upper cladding layer, the thin sections being of sufficient thinness to be readily gauged by optical interferometrical techniques; using MOCVD techniques to grow a buffer layer over the thin etched portions of the upper cladding layer of predetermined thickness, the buffer layer being of AlGaAs and having an aluminum content which is substantially the same as that of the upper cladding layer such that said buffer layer and upper cladding layer function as a composite layer having a combined refractive index mismatched with that of the active layer; growing a current blocking layer over the buffer layer, and forming a contact layer and electrodes to produce a completed semiconductor device having a p-n junction at the active layer so that when said device is energized carriers are injected into the active layer in the region defined by the mesa; the thickness of the composite cladding and buffer layers being coordinated to the width of the mesa to produce a sufficiently thick composite layer for causing said laser when energized to function in the self-pulsation mode.

Claim 5

A method of producing a semiconductor laser device capable of oscillation in a self-pulsation mode, said method comprising the steps of: growing a lower cladding layer, an active layer and an upper cladding layer on a semiconductive substrate, the cladding layers and the active layer all being of AlGaAs with the aluminum molar proportion of the active layer being lower than that of the cladding layers, the cladding layers being of opposite conductivity types thereby to form a p-n junction at the active layer; etching the upper cladding layer to form a central mesa separated by comparatively thin sections of the upper cladding layer, the thin sections of the upper cladding layer being no more than about 0.3 microns in thickness; using MOCVD techniques to grow a buffer layer over the thin etched portions of the upper cladding layer of predetermined thickness, the buffer layer being of AlGaAs to produce with the thin sections of the upper cladding layer a composite layer having a combined refractive index mismatched with that of the active layer; growing a current blocking layer over the buffer layer, and forming a contact layer and electrodes to produce a completed semiconductor device having a p-n junction at the active layer so that when said device is energized carriers are injected into the active layer in the region defined by the mesa; the thickness of the composite cladding and buffer layers being coordinated to the width of the mesa to produce a sufficiently thick composite layer for causing said laser when energized to function in the self-pulsation mode.

Claim 6

A method of producing a semiconductor laser device capable of oscillation in a self-pulsation mode, said method comprising the steps of: growing a lower cladding layer, an active layer and an upper cladding layer on a semiconductive substrate, the cladding layers and the active layer all being of AlGaAs with the aluminum molar proportion of the active layer being lower than that of the cladding layers, the cladding layers being of opposite conductivity types thereby to form a p-n junction at the active layer; etching the upper cladding layer to form a central mesa separated by comparatively thin sections of the upper cladding layer, the thin sections of the upper cladding layer being no more than about 0.3 microns in thickness; using MOCVD techniques to grow a buffer layer over the thin etched portions of the upper cladding layer of predetermined thickness, the buffer layer being of AlGaAs to produce with the thin sections of the upper cladding layer a composite layer having a combined refractive index mismatched with that of the active layer; growing a current blocking layer over the buffer layer, and forming a contact layer and electrodes to produce a completed semiconductor device having a p-n junction at the active layer so that when said device is energized carriers are injected into the active layer in the region defined by the mesa; the thickness of the composite cladding and buffer layers being coordinated to the width of the mesa to produce a sufficiently thick composite layer for causing said laser when energized to function in the self-pulsation mode.