Method for Manufacturing a Buried Hetero-Junction Type Semiconductor Laser

Claim 2

A semiconductor laser, characterized by a semiconductor substrate (1) having a first and second surface on its opposite sides; first lower (2) and second upper (5) cladding layers on said first surface; an active layer (4) between said first lower and second upper cladding layers (2,5); a cap layer (6) atop said second cladding layer (5); an insulating layer (7) atop said cap layer (6); a first electrode (8) atop said insulating layer (7); a second electrode (9) formed on said second surface of said semiconductor substrate (1); a feature (la) on said first surface of said semiconductor substrate (1) so configured that said first cladding layer (2) atop said feature (la) is sloped to either side of said feature (la), on which slopes (2a) substantially no active layer can grow during epitaxial growth of said active layer (4), whereby said feature (la) induces discontinuities in said active layer (4) at said slopes (2a); and a channel (7a) passing through said insulating layer (7) at a position opposite said feature (la) through which said first electrode (8) can oppose a section of said active layer (4) atop said feature (lb), thereby forming a resonating region therebetween.

Claim 3

A semiconductor laser as set forth in claim 1, characterized in that said semiconductor substrate (1) is formed of a conductive n-type semiconductor.

Claim 4

A semiconductor laser as set forth in claim 2, characterized in that said first and second cladding layers (2,5) are conductive layers of opposite polarity.

Claim 5

A semiconductor laser as set forth in claim 3, characterized in that said active layer (4) is of the same polarity as said first cladding layer (2).

Claim 6

A semiconductor laser as set forth in claim 4, characterized in that said feature (la) is a mesa defining a pair of slopes along opposite edges thereof, which slopes induce growth of slopes (2a) in said first cladding layer (2) during epitaxial growth of said first cladding layer (2) and having crystal faces on which the epitaxial growth rate of semiconductor layers thereon is significantly slower than other faces.

Claim 7

A semiconductor laser as set forth in claim 5, characterized in that the crystal face of said slopes (2a) of said first cladding layer (2) is the (III) B crystal surface.

Claim 8

A semiconductor laser as set forth in claim 6, characterized in that the crystal face of said first surface is the (100) crystal face.

Claim 9

A semiconductor laser as set forth in claim 7, characterized in that said semiconductor is a AlGaAs system compound.

Claim 10

A semiconductor laser as set forth in claim 8, characterized in that said semiconductor substrate (1) is an n-type GaAs system, III - V family compound.

Claim 11

A semiconductor laser as set forth in claim 9, characterized in that said first cladding layer (2) is made of n-type Al x Ga 1-x As, said second cladding layer (5) is made of p-type Al x Ga 1-x As.

Claim 12

A semiconductor laser as set forth in claim 10, characterized in that said active layer (4) is made of Al y Ga 1-y As, and wherein x > y.

Claim 13

A semicondutor laser as set forth in claim 11, further characterized by an optical waveguide layer (3) between said active layer (4) and said first cladding layer (2).

Claim 14

A semiconductor laser, characterized by a semiconductor substrate (1) having a first and second surfaces on its opposite sides, first lower (2) and second upper (5) cladding layers on said first surface, an active layer (4) between said first lower and second upper cladding layers (2,5), a cap layer (6) over said second cladding layer (5), an insulator layer (7) over said cap layer (6), a first electrode (8) over said insulator layer (7), a second electrode (9) on said second surface of said semiconductor substrate (1), in which at least said first and second cladding layers (2,5) and said active layers (4) are formed by a sequence of epitaxial growth steps, and a production process for producing said semiconductor laser including a step of forming a feature (la) on said first surface of said semiconductor substrate (1) so configured that said first cladding layer (2) atop said feature (la) is sloped to either side of said feature (la), on which slopes (2a) substantially no active layer can grow during epitaxial growth thereof, so that said feature (la) induces discontinuities in said active layer (4) opposite said slopes (2a), said feature forming step being performed prior to any epitaxial growth steps, said semiconductor layer production process further including a step of forming a channel (7a) through said insulator layer (7) at a position opposite said feature (la) through which said first electrode (8) opposes a section of said active layer (4) above said feature (la) so as to form a resonating region therebetween.

Claim 15

A semiconductor laser, characterized by a semiconductor substrate (1) having a first and second surfaces on its opposite sides, first lower (2) and second upper (5) cladding layers on said first surface, an active layer (4) between said first lower and second upper cladding layers (2,5), a cap layer (6) over said second cladding layer (5), an insulator layer (7) over said cap layer (6), a first electrode (8) over said insulator layer (7), a second electrode (9) on said second surface of said semiconductor substrate (1), in which at least said first and second cladding layers (2,5) and said active layers (4) are formed by a sequence of epitaxial growth steps, and a production process for producing said semiconductor laser including a step of forming a feature (la) on said first surface of said semiconductor substrate (1) so configured that said first cladding layer (2) atop said feature (la) is sloped to either side of said feature (la), on which slopes (2a) substantially no active layer can grow during epitaxial growth thereof, so that said feature (la) induces discontinuities in said active layer (4) opposite said slopes (2a), said feature forming step being performed prior to any epitaxial growth steps, said semiconductor layer production process further including a step of forming a channel (7a) through said insulator layer (7) at a position opposite said feature (la) through which said first electrode (8) opposes a section of said active layer (4) above said feature (la) so as to form a resonating region therebetween.

Claim 16

A semiconductor laser as set forth in claim 13, characterized in that said semiconductor substrate (1) is made of a conductive n-type semiconductor.

Claim 17

A semiconductor laser as set forth in claim 14, characterized in that said first and second cladding layers (2,5) are conductive layers of opposite polarity.

Claim 18

A semiconductor laser as set forth in claim 15, characterized in that said active layer (4) has the same polarity as said first cladding layer (2).

Claim 19

A semiconductor laser as set forth in claim 14, characterized in that said feature (la) is a mesa with a pair of slopes along either edge therof, which slopes induce growth of slopes (2a) in said first cladding layer (2) during epitaxial growth of said first cladding layer (2) and are crystal face on which the growth rate of semiconductor layers thereon is significantly slower than on other crystal faces.

Claim 20

A semiconductor laser as set forth in claim 17, characterized in that said crystal face of said slopes (2a) of said first cladding layer (2) is the (111) B crystal surface.

Claim 21

A semiconductor laser as set forth in claim 18, characterized in that the crystal face of said first surface is the (100) crystal face.

Claim 22

A semiconductor laser as set forth in claim 19, characterized in that said semiconductor is a AlGaAs system compound.

Claim 23

A semiconductor laser as set forth in claim 20, characterized in that said semiconductor substrate (1) is made of an n-type GaAs system, III - V family compound.

Claim 24

A semiconductor laser as set forth in claim 21, characterized in that said first cladding layer (2) is made of n-type AlxGa1-xAs, and said second cladding layer (5) is made of p-type Al x Ga 1-x As.

Claim 25

A semiconductor laser as set forth in claim 22, characterized in that said active layer (4) is made of Al y Ga 1-y As, and wherein x > y.

Claim 26

A semiconductor laser as set forth in claim 23, further characterized by an optical waveguide layer (3) between said active layer (4) and said first cladding layer (2).

Claim 27

A semiconductor laser as set forth in claim 13, characterized in that said feature forming step is performed by an etching process by masking said semiconductor substrate (1) at the position at which said feature (la) is to be formed.

Claim 28

A semiconductor laser as set forth in claim 25, characterized in that said sequence of epitaxial growth steps forms said first and second cladding layer (2,5), said active layer (4), said cap layer (6) and said insulating layer (7).

Claim 29

A process for producing a semiconductor laser which comprises a semiconductor substrate (1) having a first and second surfaces on its opposite sides, first lower (2) and second upper (5) cladding layers on said first surface, an active layer (4) between said first and second upper cladding layers (2,5), a cap layer (6) over said second cladding layer (5), an insulating layer (7) over said cap layer (6), a first electrode (8) oversaid insulator layer (7), and a second electrode (9) on said second surface of said semiconductor substrate (1), characterized by the steps of: forming a feature (la) on said first surface of said semiconductor substrate (1) so configured that said first cladding layer (2) atop said feature (la) is sloped to either side of said feature (la), on which slopes (2a) substantially no active layer can grow during epitaxial growth thereof, whereby said feature (la) induces discontinuities in said active layer (4); performing a sequence of epitaxial growth steps so as to form said first and second cladding layers (2,5) and said active layers (4), said cap layer (6) and said insulating layer (7); forming a channel (7a) through said insulating layer (7) at a position opposite said feature (la); and forming said first and second electrodes (8,9) on said first and second surfaces of said semiconductor substrate (1), said first electrode (8) opposing a section of said active layer (4) above said feature (la) and forming a resonating region therebetween.

Claim 30

A process for producing a semiconductor laser which comprises a semiconductor substrate (1) having a first and second surfaces on its opposite sides, first lower (2) and second upper (5) cladding layers on said first surface, an active layer (4) between said first and second upper cladding layers (2,5), a cap layer (6) over said second cladding layer (5), an insulating layer (7) over said cap layer (6), a first electrode (8) oversaid insulator layer (7), and a second electrode (9) on said second surface of said semiconductor substrate (1), characterized by the steps of: forming a feature (la) on said first surface of said semiconductor substrate (1) so configured that said first cladding layer (2) atop said feature (la) is sloped to either side of said feature (la), on which slopes (2a) substantially no active layer can grow during epitaxial growth thereof, whereby said feature (la) induces discontinuities in said active layer (4); performing a sequence of epitaxial growth steps so as to form said first and second cladding layers (2,5) and said active layers (4), said cap layer (6) and said insulating layer (7); forming a channel (7a) through said insulating layer (7) at a position opposite said feature (la); and forming said first and second electrodes (8,9) on said first and second surfaces of said semiconductor substrate (1), said first electrode (8) opposing a section of said active layer (4) above said feature (la) and forming a resonating region therebetween.

Claim 31

The process as set forth in claim 27, characterized in that said first and second cladding layers (2,5) are conductive layers of opposite polarity.

Claim 32

A process as set forth in claim 28, characterized in that said active layer (4) has the same polarity as said first cladding layer (2).

Claim 33

A process as set forth in claim 29, characterized in that said feature forming step is performed by etching said substrate (1) so as to form a mesa with a pair of slopes along either edge thereof, which slopes induce the growth of slopes (2a) in said first cladding layer (2) during epitaxial growth of said first cladding layer (2) and have crystal faces on which the epitaxial growth rate of layer material thereon is significantly slower than on other crystal faces.

Claim 34

A process as set forth in claim 30, characterized in that said crystal face of said slopes (2a) of said first cladding layer (2) is the (111) B crystal surface.

Claim 35

A process as set forth in claim 31, characterized in that the crystal face of said first surface is the (100) crystal face.

Claim 36

A process as set forth in claim 32, characterized in that said semiconductor is a AlGaAs system compound.