Semiconductor laser and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-2016126701-A1
Application number	US-201514873659-A
Country	US
Kind code	A1
Filing date	Oct 2, 2015
Priority date	Oct 31, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

In a semiconductor laser, a block layer is provided on both sides of a mesa-type semiconductor part having an n-type cladding layer, an active layer, and a p-type cladding layer. The block layer has: a p-type block layer formed on the side surface of the mesa-type semiconductor part and over a p-type semiconductor substrate; a high-resistance layer formed over the p-type block layer; and an n-type block layer formed over the high-resistance layer, which has a higher resistance than that of the p-type block layer. By providing the high-resistance layer between the p-type block layer and the n-type block layer, the thickness of the p-type block layer can be controlled and a leakage current (flow of a hole) can be reduced. Further, the distance between the n-type cladding layer and the n-type block layer can be secured, and hence a leakage current (flow of an electron) can be prevented.

First claim

1 . A semiconductor laser comprising:
a p-type semiconductor substrate; a convex part provided over the semiconductor substrate; a block layer provided on both sides of the convex part; wherein the convex part has: a p-type compound semiconductor layer formed over the semiconductor substrate; an active layer formed over the p-type compound semiconductor layer; and an n-type compound semiconductor layer formed over the active layer, and wherein the block layer has: a p-type block layer including a p-type compound semiconductor formed over a side surface of the convex part and over the semiconductor substrate; a first resistive layer formed over the p-type block layer; and an n-type block layer including an n-type compound semiconductor formed over the first resistive layer, and wherein the first resistive layer has a resistance larger than that of the p-type block layer.

2 . The semiconductor laser according to claim 1 ,
wherein the first resistive layer is a compound semiconductor into which Fe (iron) has been introduced.

3 . The semiconductor laser according to claim 1 comprising:
a second resistive layer formed over the n-type block layer.

4 . The semiconductor laser according to claim 3 ,
wherein the second resistive layer is a compound semiconductor into which Fe (iron) has been introduced.

5 . The semiconductor laser according to claim 1 ,
wherein a thickness of the p-type block layer is 0.2 μm or less.

6 . The semiconductor laser according to claim 1 ,
wherein a thickness of the p-type block layer is 0.1 μm or less.

7 . The semiconductor laser according to claim 1 ,
wherein each of the p-type compound semiconductor layer and the p-type block layer is InP including a p-type impurity, and wherein each of the n-type compound semiconductor layer and the n-type block layer is InP including an n-type impurity, and wherein the first resistive layer is InP into which Fe (iron) has been introduced.

8 . The semiconductor laser according to claim 1 comprising:
a layer including an n-type compound semiconductor formed over the convex part and the block layer,
wherein a first electrode is formed above the layer, and
wherein a second electrode is formed in a rear surface of the semiconductor substrate.

9 . The semiconductor laser according to claim 1 ,
wherein the n-type compound semiconductor layer covers a side surface of the active layer.

10 . The semiconductor laser according to claim 9 ,
wherein the block layer includes a semiconductor layer selectively grown over the semiconductor substrate.

11 . A manufacturing method of a semiconductor laser, comprising the steps of:
(a) forming a laminated film by forming a p-type compound semiconductor layer, an active layer, and an n-type compound semiconductor layer in this order from below, over a p-type semiconductor substrate; (b) forming a convex part by etching the laminated film; and (c) forming a block layer over the semiconductor substrate on both sides of the convex part,
wherein the step (c) includes the steps of:
(c1) forming a p-type block layer including a p-type compound semiconductor, over a side surface of the convex part and over the semiconductor substrate; (c2) forming a first resistive layer having a resistance larger than that of the p-type block layer, over the p-type block layer; and (c3) forming an n-type block layer including an n-type compound semiconductor, over the first resistive layer.

12 . The manufacturing method of a semiconductor laser according to claim 11 ,
wherein a thickness of the p-type block layer is 0.1 μm or less.

13 . The manufacturing method of a semiconductor laser according to claim 11 ,
wherein each of the p-type compound semiconductor layer and the p-type block layer is InP including a p-type impurity, and wherein each of the n-type compound semiconductor layer and the n-type block layer is InP including an n-type impurity, and wherein the first resistive layer is InP into which Fe (iron) has been introduced.

14 . The manufacturing method of a semiconductor laser according to claim 11 , comprising the steps of:
after the step (c) above, (d) forming a second resistive layer having a resistance larger than that of the p-type block layer, over the n-type block layer; (e) forming a layer including an n-type compound semiconductor, over the convex part and the block layer; and (f) forming a first electrode above the layer and forming a second electrode in a rear surface of the semiconductor substrate.

15 . The manufacturing method of a semiconductor laser according to claim 14 ,
wherein each of the p-type compound semiconductor layer and the p-type block layer is InP including a p-type impurity, and wherein each of the n-type compound semiconductor layer and the n-type block layer is InP including an n-type impurity, and wherein each of the first resistive layer and the second resistor layer is InP into which Fe (iron) has been introduced; and wherein a thickness the p-type block layer is 0.1 μm or less.

16 . A manufacturing method of a semiconductor laser, comprising the steps of:
(a) forming a convex part, in which a p-type compound semiconductor layer, an active layer, and an n-type compound semiconductor layer are laminated in this order from below, over a p-type semiconductor substrate; and (b) forming a block layer over the semiconductor substrate on both sides of the convex part,
wherein the step (a) includes the steps of:
(a1) forming a mask having an opening in a first region, over the semiconductor substrate; (a2) forming the p-type compound semiconductor layer, the active layer, and the n-type compound semiconductor layer in this order from below, over the semiconductor substrate exposed from the opening; and (a3) removing the mask, and
wherein the step (b) includes the steps of:
(b1) forming a p-type block layer including a p-type compound semiconductor, over a side surface of the convex part and over the semiconductor substrate; (b2) forming a first resistive layer having a resistance larger than that of the p-type block layer, over the p-type block layer; and (b3) forming an n-type block layer including an n-type compound semiconductor, over the first resistive layer.

17 . The manufacturing method of a semiconductor laser according to claim 16 ,
wherein the step (a2) is a step of forming the n-type compound semiconductor layer over an upper surface and a side surface of the active layer, after the p-type compound semiconductor layer and the active layer are formed in this order from below, over the semiconductor substrate exposed from the opening.

18 . The manufacturing method of a semiconductor laser according to claim 16 ,
wherein each of the p-type compound semiconductor layer and the p-type block layer is InP including a p-type impurity, and wherein each of the n-type compound semiconductor layer and the n-type block layer is InP including an n-type impurity, and wherein the first resistive layer is InP into which Fe (iron) has been introduced.

19 . The manufacturing method of a semiconductor laser according to claim 17 , comprising the steps of:
after the step (b) above, (c) forming a second resistive layer having a resistance larger than that of the p-type block layer, over the n-type block layer; (d) forming a layer including an n-type compound semiconductor, over the convex part and the block layer; and (e) forming a first electrode above the layer and forming a second electrode in a rear surface of

Assignees

• Renesas Electronics Corp

Inventors

• Okuda Tetsuro

Classifications

• H01S2304/04

  MOCVD or MOVPE · CPC title

• H01S5/34306

  emitting light at a wavelength longer than 1000nm, e.g. InP based 1300 and 1500nm lasers · CPC title

• H01S5/2272

  grown by a mask induced selective growth · CPC title

• H01S5/2224

  semi-insulating semiconductors · CPC title

• H01S5/2222

  having special electric properties · CPC title