SEMICONDUCTOR LASER

Abstract

A semiconductor laser having an n-cladding layer, an optical guide layer, an active layer, an optical guide layer, and a p-cladding layer above an InP substrate, in which the active layer has a layer constituted with Be-containing group II-VI compound semiconductor mixed crystals, and at least one of layers of the n-cladding layer, the optical guide layer, and the p-cladding layer has a layer constituted with elements identical with those of the Be-containing group II-VI compound semiconductor mixed crystals of the active layer, and the layer is constituted with a superlattice structure comprising, as a well layer, mixed crystals of a Be compositions with the fluctuation of the composition being within ±30% compared with the Be composition of the group II-VI compound semiconductor mixed crystals of the active layer, whereby the device characteristics of the semiconductor laser comprising the Be-containing group II-VI compound semiconductor matched with the InP substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross sectional view of a BeZnSeTe series light emitting diode or a semiconductor laser prepared on an InP substrate of an existent structure;

FIG. 1B is a view showing a band line-up of the light emitting diode or the semiconductor laser;

FIG. 2A is a schematic cross sectional view of a semiconductor laser according to the present invention;

FIG. 2B is a view showing a band line-up of the semiconductor laser;

FIG. 3A is a graph showing comparison of the result of calculation for the dependence of the optical confinement factor to the active layer by an MgSe/ZnCdSe optical guide layer of an existent structure and the optical confinement factor to the active layer by an MgSe/BeZnSeTe optical guide layer of the structure of the invention on the thickness of a BeZnSeTe acting layer;

FIG. 3B is a graph showing comparison of the result of calculation for the dependence of the threshold current density in each of the semiconductor lasers of the existent structure and the semiconductor laser of the invention on the thickness of the BeZnSeTe active layer;

FIG. 4 is a schematic cross sectional view showing the structure of a BeZnSeTe sample;

FIG. 5A is a graph showing a photoluminescence peak wavelength and a photoluminescence full width at half maximum value of a experimentally manufactured BeZnSeTe sample relative to a Be composition;

FIG. 5B is a graph showing the calculation value of the band gap energy of the BeZnSeTe sample lattice-matched to an InP substrate relative to a Be composition;

FIG. 6 is a schematic cross sectional view showing the structure of an MgSe/BeZnSeTe superlattice sample;

FIG. 7 is a graph showing a relation between the time of Zn irradiation and the photoluminescence emission intensity of the MgSe/BeZnSeTe superlattice;

FIG. 8 is a graph showing the photoluminescence spectrum of an MgSe/BeZnSeTe superlattice;

FIG. 9 is a graph showing a relation between the Mg composition of an MgSe/BeZnSeTe superlattice and photoluminescence emission energy;

FIG. 10 is a graph showing a relation between the Mg composition of an MgSe/BeZnSeTe superlattice and the photoluminescence emission intensity;

FIG. 11A is a schematic cross sectional view of an n-MgSe/BeZnSeTe/ZnCdSe superlattice sample structure for measurement of a carrier concentration;

FIG. 11B is a view showing a band line-up of a sample structure;

FIG. 12A is a schematic cross sectional view of a p-MgSe/ZnSeTe/BeZnSeTe superlattice sample structure for measurement of a carrier concentration;

FIG. 12B is a view showing the band line-up of the sample structure;

FIG. 13A is a schematic cross sectional view showing a semiconductor laser structure of an example of the present invention;

FIG. 13B is a view showing a band line-up of the semiconductor laser structure;

FIG. 14A is a schematic cross sectional view showing a semiconductor laser structure of another example of the present invention;

FIG. 14B is a view showing a band line-up of the semiconductor laser structure;

FIG. 15A is a schematic cross sectional view showing a semiconductor laser structure of a further example of present the invention; and

FIG. 15B is a view showing a band line-up of the semiconductor laser structure.

Claims

1. A semiconductor laser having an n-cladding layer, a first optical guide layer, an active layer, a second optical guide layer, and a p-cladding layer above an InP substrate, wherein the active layer has a Be-containing group II-VI compound semiconductor mixed crystal layer,having a layer constituted with a matrix element identical with that of the Be-containing group II-VI compound semiconductor of the active layer in any one of the following layer configurations (1) to (8):

2. A semiconductor laser according to claim 1, wherein the band gap Ega of the layer having the Be compositional ratio Xa constituting any one of the layer configurations (1) to (8) and the band gap Egb of the layer having the Be compositional ratio Xb of the active layer satisfy a relation: 0.7×Egb<Ega<1.3×Egb

3. A semiconductor laser according to claim 1, wherein the active layer is constituted with Bex1Zn1-x1SeY1Te1-Y1 mixed crystals, or constituted with a stacked structure of the Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer and another crystal layer; andat least one of the optical guide layer, the p-cladding layer, and the n-cladding layer is formed of a superlattice structure of a Bex2Zn1-x2SeY2Te1-Y2 mixed crystal well layer and a barrier layer constituted with other crystals, wherea relation: 0.7×X1<X2<1.3×X1 and 0.7×Y1<Y2<1.3×Y1 is satisfied.

4. A semiconductor laser according to claim 1, wherein the active layer is constituted with Bex1Zn1-x1SeY1Te1-Y1 mixed crystals, or constituted of a stacked structure of the Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer and another crystal layer containing MgSe; andat least one of layers of the optical guide layer, the p-cladding layer, and the n-cladding layer is formed of a superlattice structure comprising Bex2Zn1-x2SeY2Te1-Y2 mixed crystals as a well layer and MgSe crystals as a barrier layer, wherea relation: 0.7×X1<X2<1.3×X1 and 0.7×Y1<Y2<1.3×Y1 is satisfied.

5. A semiconductor laser according to claim 4, wherein the thickness of the MgSe barrier layer is from 1 to 5 monolayers.

6. A semiconductor laser having an n-cladding layer, an optical guide layer, an active layer, an optical guide layer, and a p-cladding layer on an InP substrate, whereinthe active layer is constituted with Bex1Zn1-x1SeY1Te1-Y1 mixed crystals, or constituted of a stacked structure of a Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer and another crystal layer containing MgSe,the p-cladding layer is constituted of a superlattice structure comprising, as main constituent elements, a Bex2Zn1-x2SeY2Te1-Y2 mixed crystals and an MgSe layer having a thickness of 1 to 5 monolayers, where relation: 0.7×X1<X2<1.3×X1 and 0.7×Y1<Y2<1.3×Y1 is satisfied.

7. A semiconductor laser according to claim 6, wherein the p-cladding layer is constituted of a superlattice structure comprising, as the main constituent element, at least one of a ZnSeTe layer, a ZnBeTe layer, a ZnTe layer, a MgZnSeTe layer, an MgZnTe layer, or BeTe layer, in addition to the Bex2Zn1-x2SeY2Te1-Y2 mixed crystals and the MgSe layer having a thickness of 1 to 5 monolayers.

8. A semiconductor laser having an n-cladding layer, an optical guide layer, an active layer, an optical guide layer, and a p-cladding layer on an InP substrate, wherein the active layer is constituted with Bex1Zn1-x1SeY1Te1-Y1 mixed crystals, or constituted of a stacked structure of the Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer and another crystal layer containing MgSe; andthe n-cladding layer is constituted with a superlattice structure comprising, as the main constituent element, a Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer and an MgSe layer having a thickness of 1 to 5 monolayers, wherea relation: 0.7×X1<X2<1.3×X1 and 0.7×Y1<Y2<1.3×Y1 is satisfied.

9. A semiconductor laser according to claim 8, wherein the n-cladding layer is constituted of a superlattice structure comprising, as the main constituent element, at least one of an MgZnSe layer, an MgCdSe layer, a ZnCdSe layer, a ZnSe layer, a CdSe layer, an MgZnCdSe layer, a BeSe layer, a BeZnSe layer, a BeCdSe layer, a BeZnCdSe layer, an MgZnSeTe layer, and a ZnSeTe layer in addition to the Bex2Zn1-x2SeY2Te1-Y2 mixed crystal layer and the MgSe layer having a thickness of 1 to 5 monolayers.

10. A method of manufacturing a semiconductor laser having an n-cladding layer, an optical guide layer, an active layer, an optical guide layer, and a p-cladding layer constituted with a group II-VI compound semiconductor formed on an InP substrate by a molecular beam epitaxial method, wherein the active layer is constituted with Bex1Zn1-x1SeY1Te1-Y1 mixed crystals or constituted of a stacked structure of a Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer and another crystal layer containing MgSe,at least one of the optical guide layer, the p-cladding layer, and the n-cladding layer is constituted of a superlattice structure comprising, as a well layer, mixed crystals of a composition identical with the BeZnSeTe mixed crystals of the active layer, andZn irradiation is conducted for a predetermined time before and/or after forming the BeZnSeTe mixed crystals in the formation of the superlattice structure and the stacked structure containing the BeZnSeTe mixed crystals.

11. A method of manufacturing a semiconductor laser according to claim 10, wherein the active layer is constituted with the Bex1Zn1-x1SeY1Te1-Y1 mixed crystal layer or constituted of a stacked constitution having the Bex2Zn1-x2SeY2Te1-Y2 mixed crystal layer and the MgSe layer.

12. A semiconductor laser according to claim 1, wherein at least one of the optical guide layer, the p-cladding layer, and the n-cladding layer is constituted of a superlattice structure having a mixed crystal well layer and the MgSe barrier layer of a composition identical with that of the BeZnSeTe mixed crystals of the active layer, and constituted of a superlattice structure having a Zn containing layer of 2 atom layers or less between the mixed crystal well layer and the MgSe barrier layer.

13. A semiconductor laser according to claim 2, wherein the Bex1Zn1-x1SeY1Te1-Y1 mixed crystals constituting the active layer are lattice matched with the InP substrate at a lattice mismatching degree within 1%, where a relation: 0.01<X1<0.3 is satisfied.

14. A semiconductor laser according to claim 3, wherein the Bex1Zn1-x1SeY1Te1-Y1 mixed crystals constituting the active layer are lattice matched with the InP substrate at a lattice mismatching degree within 1%, where a relation: 0.01<X1<0.3 is satisfied.

15. A semiconductor laser according to claim 4, wherein the Bex1Zn1-x1SeY1Te1-Y1 mixed crystals constituting the active layer are lattice matched with the InP substrate with a lattice mismatching degree of 1% or less, where a relation: 0.01<X1<0.3 is satisfied.

16. A semiconductor laser according to claim 6, wherein the Bex1Zn1-x1SeY1Te1-Y1 mixed crystals constituting the active layer are lattice matched with the InP substrate with a lattice mismatching degree of 1% or less, where a relation: 0.01<X1<0.3 is satisfied.

17. A semiconductor laser according to claim 8, wherein the Bex1Zn1-x1SeY1Te1-Y1 mixed crystals constituting the active layer are lattice matched with the InP substrate with a lattice mismatching degree of 1% or less, where a relation: 0.01<X1<0.3 is satisfied.

18. A semiconductor laser according to claim 2, wherein the active layer is constituted of a quantum well structure,any one of superlattices constituted with Bex1Zn1-x1SeY1Te1-Y1 mixed crystals or MgSe/Bex1Zn1-x1SeY1Te1-Y1 mixed crystals is used as the well layer for constituting the quantum well structure, andany one of superlattices constituted with Bex2Zn1-x2SeY2Te1-Y2 mixed crystals or MgSe/Bex2Zn1-x2SeY2Te1-Y2 mixed crystals is used as the barrier layer for constituting the quantum well structure, wherea relation: 0.7×X1<X2<1.3×X1 and 0.7×Y1<Y2<1.3×Y1 is satisfied.