JP2009212272A - Semiconductor device, semiconductor laser and method for manufacturing the semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device having a low temperature dependence, a semiconductor laser and a method for manufacturing the semiconductor device. <P>SOLUTION: In this semiconductor device 1, which includes a substrate 2 and an active layer 4 constituted of an Sb-based semiconductor thin film formed on the substrate 2, the active layer 4 is formed on a surface of the substrate 2 in which the crystal orientation being (111). The active layer 4 is the Sb-based semiconductor thin film formed of any one kind or two kinds or more of GaSb, AlGaSb, AlSb, InGaSb and InSb, and has a quantum well structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device, a semiconductor laser, and a semiconductor device manufacturing method, and is particularly suitable for application to a semiconductor device having a multiple quantum well structure.

  Currently, 1.3-1.55 μm band semiconductor lasers are used for optical communications. In this wavelength region, a semiconductor laser is manufactured mainly using a substrate having an InP (001) plane orientation (for example, Patent Document 1). By the way, if an Si substrate can be used instead of an InP substrate, it is expected that a very inexpensive semiconductor laser in the infrared region can be realized.

On the other hand, miniaturization has progressed in silicon integrated circuits, and there is a need for optoelectronic integration for further integration and higher functionality. For example, in the optical interconnect, it is considered that the 1.3-1.5 μm band infrared wavelength region conventionally used in optical communication is suitable. In general, from such a technical background, research and development for epitaxial growth of compound semiconductors on Si substrates are underway, and candidates for this include Sb-based semiconductors.
JP-A-6-69589

  However, the conventional Sb-based semiconductor has a problem that the emission wavelength varies depending on the operating temperature range.

  In view of the above-described problems, an object of the present invention is to provide a semiconductor element, a semiconductor laser, and a method for manufacturing the semiconductor element that have low temperature dependency.

  To achieve the above object, the invention according to claim 1 is a semiconductor device comprising a substrate and an active layer made of an Sb-based semiconductor thin film formed on the substrate, wherein the active layer has a crystal orientation of (111 ) On the surface of the substrate.

  According to a second aspect of the present invention, the active layer is an Sb-based semiconductor thin film formed of one or more of GaSb, AlGaSb, AlSb, InGaSb, and InSb, and has a quantum well structure. It is characterized by having.

  According to a third aspect of the present invention, the active layer includes a well layer formed of a GaSb thin film and a barrier layer formed of an AlGaSb thin film, wherein the Al composition is 0.3 to 0.4, and the well layer The thickness of the barrier layer is 8 to 9 nm, and the thickness of the barrier layer is 40 to 50 nm.

  The invention according to claim 4 is a semiconductor device comprising a substrate, an active layer made of an Sb-based semiconductor thin film formed on the substrate, and a pair of clad layers formed so as to sandwich the active layer. The active layer includes a semiconductor element formed on the surface of the substrate having a crystal orientation of (111).

  The invention according to claim 5 is a method of manufacturing a semiconductor device comprising a step of forming an active layer made of an Sb-based semiconductor thin film on a substrate, wherein the active layer has a crystal orientation of (111). It is characterized by being formed by epitaxial growth on the surface.

  The invention according to claim 6 is characterized in that the epitaxial growth temperature is 400 ° C. to 500 ° C.

  According to the present invention, a semiconductor element having low temperature dependence can be obtained, so that a highly reliable semiconductor laser that can be stably used can be formed at low cost. If low-cost optical device technology using such a Si (111) substrate is realized, it can be installed in, for example, transportation equipment such as an automobile, and the safety of the driver during night driving can be improved. it can.

(1) Overall Configuration A preferred embodiment of the present invention will be described below with reference to the drawings. A semiconductor element 1 shown in FIG. 1 includes a substrate 2, a first cladding layer (n-type) 3, an active layer 4, and a second cladding layer (p-type) 5, and the first cladding layer 3, Both the active layer 4 and the second cladding layer 5 are made of an Sb-based semiconductor thin film, and are sequentially laminated on the substrate 2. As a result of examining the semiconductor element 1 configured as described above, it was confirmed that the emission wavelength varies depending on the operating temperature range.

  Therefore, as a result of examining semiconductor devices, semiconductor lasers, and semiconductor device manufacturing methods having low temperature dependence, it was confirmed that temperature dependence can be improved by controlling the crystal orientation of the substrate surface 2 on which the active layer 4 is laminated. did.

  That is, the substrate 2, the first clad layer 3, the active layer 4, and the second clad layer 5 are included, and the first clad layer 3, the active layer 4, and the second clad layer 5 are any of them. In a semiconductor element made of an Sb-based semiconductor thin film and sequentially stacked on the substrate 2, it is desirable that the crystal orientation of the surface of the substrate 2 on which the first cladding layer 3 is stacked be (111).

  In the present embodiment, the substrate 2 is made of Si (111). The first cladding layer 3 is formed by sequentially laminating an AlSb layer 3a and a GaSb layer 3b on the surface of the Si substrate 2. The active layer 4 is formed of any one or more of GaSb, AlGaSb, AlSb, InGaSb, and InSb. Although not shown, the active layer 4 is preferably a multiple quantum well (MQW) structure in which a plurality of well layers formed of GaSb thin films and barrier layers formed of AlGaSb thin films are alternately stacked.

  A mechanism for reducing the temperature dependence will be described. It is considered that light emission by conventional Si (001) reflects the temperature dependence of the band gap. On the other hand, for a substrate made of Si having a crystal orientation of (111) according to the present invention, in addition to the temperature change of the band gap, the influence on the band gap due to the strain received from the substrate can be considered. It is thought that the temperature dependence is reduced by offsetting the influence of strain.

  Next, a method for forming an Sb-based semiconductor thin film according to the present invention will be described. In the present embodiment, a case of forming by molecular beam epitaxy (MBE method) will be described.

  In the present embodiment, a first cladding layer 3 is formed on a Si substrate 2 having a crystal orientation of (111). In order to form the first cladding layer 3, first, the AlSb layer 3a is formed. After confirming the formation of the AlSb layer 3a, the GaSb layer 3b is epitaxially grown. At that time, the GaSb layer 3b can realize a flat crystal surface by two-dimensional growth.

  After forming the first cladding layer 3 in this manner, in this embodiment, an active layer 4 having a multiple quantum well structure including a well layer formed of a GaSb thin film and a barrier layer formed of an AlGaSb thin film is manufactured. Next, FIG. 2 is a structural diagram in the case where a surface emitting laser (VCSEL) 10 as a semiconductor element is manufactured using the Si substrate 2 having the crystal orientation (111) as described above. is there. A surface emitting laser 10 includes a substrate 2, a first DBR (Distributed Bragg Reflection) layer 11 as a first cladding layer, an active layer 12, and a second DBR layer 13 as a second cladding layer. The first DBR layer 11, the active layer 12, and the second DBR layer 13 are sequentially stacked on the substrate 2. The substrate 2 is made of Si having a crystal orientation (111) containing an n-type impurity. The first DBR layer 11 is formed on the substrate 2 and includes an AlGaSb layer and a GaSb layer containing impurities of the same type as the substrate 2. Although not shown, the active layer 12 has a multiple quantum well structure including a well layer formed of a GaSb thin film and a barrier layer formed of an AlGaSb thin film. The second DBR layer 13 is made of an impurity of the opposite type to the first DBR layer 11, that is, a p-type GaSb layer. Further, a first electrode 15 is provided on the lower surface of the substrate 2, and a second electrode 14 having a window 17 on the second DBR layer 13 and the polyimide 16 is provided.

In the surface emitting laser 10 having such a structure, a resonator is formed in a direction perpendicular to the substrate 2 by the first DBR layer 11 and the second DBR layer 12 provided on both sides of the active layer 12, respectively. Thereby, the surface emitting laser 10 can emit light from the surface of the substrate 2. Thus, in this embodiment, the surface emitting laser 10 having low temperature dependence can be provided by forming the active layer 11 on the Si substrate 2 having the crystal orientation (111). In this embodiment, the substrate 2 is formed using Si having a crystal orientation of (111). However, the structure shown here is an Sb-based semiconductor multiple quantum well structure on a semiconductor substrate different from the GaSb substrate, for example, GaAs (111 It goes without saying that the same effect can be expected when fabricated on an InP (111) substrate.
(2) Examples Hereinafter, examples will be described. For the substrate, Si having a crystal orientation of (111) is used, and an AlSb layer is first formed to a thickness of 10 nm. After the formation is confirmed, the GaSb layer is epitaxially grown to a thickness of 500 nm.

Next, an active layer is formed on the Si substrate having the crystal orientation (111) on which the first cladding layer is formed as described above. The formation conditions are as shown in FIG. That is, a Si substrate having a crystal orientation of (111) is set in a thin film growth chamber having a back pressure of 10 ⁻⁸ Torr or less. Thereafter, degassing of the surface is performed at 300 ° C., and the natural oxide film on the surface of the Si substrate having a crystal orientation of (111) is removed at 750 ° C. After that, the substrate temperature is lowered to 500 ° C. while irradiating the antimony molecular beam, and after the formation of the AlSb layer and the GaSb layer, a multiple quantum composed of a well layer formed of a GaSb thin film and a barrier layer formed of an AlGaSb thin film A well structure is produced. The multiple quantum well structure of this example has 10 quantum wells with an Al composition of 0.35. Next, a second cladding layer is formed to a thickness of 5 nm.

  The X-ray diffraction measurement result of the epitaxial layer thus formed is shown in FIG. It was confirmed that the (111) plane of the GaSb layer formed on the Si substrate having the crystal orientation (111) was epitaxially grown. Furthermore, the result of having measured the photoluminescence about this multiple quantum well structure is shown in FIG. Measurements from 15K to 300K were performed. The results of FIG. 5 are summarized in the graph of FIG. From this measurement result, in the conventionally reported multiple quantum well structure (A in the figure) grown on the surface of (100) Si, the emission wavelength is shifted to the longer wavelength side. However, it was confirmed that no strong temperature dependence appears in the multiple quantum well structure (B in the figure) grown on the surface of (111) Si. As a result, it was confirmed that the multiple quantum well structure (B in the figure) grown on the Si surface having the crystal orientation (111) is optimal as the plane index of Si for producing an optical device. Thus, when a semiconductor laser is formed on the Si (111) surface, it has become possible to realize a semiconductor laser having excellent temperature dependence.

  The present invention is not limited to this embodiment, and various modifications can be made within the scope of the gist of the present invention.

  Future industrial applications of this research include the realization of integrated technology using low-cost infrared light emitting / receiving devices fabricated on Si substrates, for example, pedestrian recognition when driving a car at night using an infrared light receiving element array It is expected that it will be able to achieve safe driving.

It is sectional drawing which shows typically the structure of the semiconductor element which concerns on this embodiment. It is a perspective sectional view showing typically the composition of the surface emitting laser concerning this embodiment. It is a figure which shows the relationship between the substrate temperature and time which show the manufacturing conditions of a semiconductor element. It is a figure which shows the result of the X-ray-diffraction crystal structure analysis of a semiconductor element. It is a figure which shows the measurement result of the photoluminescence of a semiconductor element. It is a figure which shows the relationship between temperature and peak energy newly, and temperature and peak wavelength from the result of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 Board | substrate 3 1st cladding layer 4 Active layer 5 2nd cladding layer

Claims (6)

  In a semiconductor device comprising a substrate and an active layer made of an Sb-based semiconductor thin film formed on the substrate, the active layer is formed on the surface of the substrate having a crystal orientation of (111) Semiconductor element.   2. The active layer is an Sb-based semiconductor thin film formed of any one or more of GaSb, AlGaSb, AlSb, InGaSb, and InSb, and has a quantum well structure. Semiconductor element.   The active layer includes a well layer formed of a GaSb thin film and a barrier layer formed of an AlGaSb thin film, the Al composition is 0.3 to 0.4, and the thickness of the well layer is 8 to 9 nm. 2. The semiconductor device according to claim 1, wherein the thickness of the layer is 40 to 50 nm.   In a semiconductor element comprising a substrate, an active layer made of an Sb-based semiconductor thin film formed on the substrate, and a pair of clad layers formed so as to sandwich the active layer, the active layer has a crystal orientation of (111 And a semiconductor element formed on the surface of the substrate.   In a method for manufacturing a semiconductor device comprising a step of forming an active layer made of an Sb-based semiconductor thin film on a substrate, the active layer is formed by epitaxial growth on the surface of the substrate having a crystal orientation of (111). A method for manufacturing a semiconductor device.   6. The method of manufacturing a semiconductor device according to claim 5, wherein the epitaxial growth temperature is 400 to 500.degree.

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