JPS5853878A - Infrared laser element - Google Patents

Abstract

PURPOSE:To prevent crack and improve yield of chipping in a compound semiconductor laser element including Pb by making the lattice constant of crystal layer at the upper part of crystal layer of light emitting region equal to that of the crystal layer in the light emitting region. CONSTITUTION:A P type Pb1-xSnxTe 22, P type Pb1-xSnxTe active layer 23 and an N type PbTe1-ySey24 are epitaxially grown in the liquid phase on the P type PbTe 21. When the lattice constant of the upper layer 24 of the active layer is made equal to that of the active layer, any crack is not generated in case of forming cleavage on the crystal and the yield of chipping can be improved. Moreover, any crystal defect is not generated in the vicinity of interface between the layers 23 and 24 owing to the lattice alignment and accordingly the laser beam emitting efficiency is not lowered.

Description

[Detailed description of the invention] The present invention relates to improvements in infrared radar elements.

Giesejap is mourned as a material for chivalry (infrared red leaf).

The structure of an infrared laser element formed using such a lead-containing compound conductor is the first! ! ] and shown in FIG.

First, as shown in the first mK, the structure of the conventional infrared laser element is P-type PbTe tv-based f? 'K Pb r -z8
A crystal layer of nzTs serves as a first cladding layer 2, and a crystal layer of Pb>-x8nxTe with a changed X value serves as an active layer 3 serving as a region for Raded emission. ) T-48n3cT6 crystal layers are each formed as the second cladding layer 4 by a liquid phase eviaxial growth method.

The reason why the active layer 3 is sandwiched between the upper and lower crystal layers 2 and 4 having a composition different from that of the active layer is that the bunt cap and refractive index of each crystal layer are determined at the interface between the active layer 3 and the crystal N2.4. In this way, the 1kI
The No. 14 laser element is called a double hetero type Rade element.

By the way, in the laser element having the structure described above, the Pbr-x8nxTe crystal layer forming the active layer and the Pb5-z8nxT crystal layer forming the first and second cladding layers have different lattice constants. Active layer 3 and cladding layer 2.4. When the active layer 3 and the cladding layer 2.4 are formed by liquid phase epitaxial growth, a state of lattice mismatch occurs in which the lattices between the respective crystals do not match at the interface 6.6 between the active layer 3 and the cladding layer 2.4. Such a lattice mismatch state tends to cause lattice defects in that part, causing injected carriers to be trapped in that part, resulting in an increase in the threshold μ value current density of the device for starting Radical emission. 〇 Figure 2 shows the structure of a nine-laser device that improves this defect 1.〇 As shown in the figure, a P-type 1 cladding layer 12 is formed on a P-type PbTρ substrate 11, and a The active layer 1 is a P-type lead tin telluride (Pb-x8nzTa) crystal layer.
3, as well as KN type lead tellurium selenide (
The crystal layer of PbT@t-y8sy) is the second cladding layer 1.
It is formed as 4.

Here, although the active layer 13 and the cladding layers 12 and 14 have different compositions, their lattice constants match, so lattice defects due to lattice mismatch are not formed at the interface between the active layer 13 and the cladding 1112.14, as described above. Therefore, the threshold current density of the device that starts emitting light can now be about % of the conventional value.

However, the Pb forming the claddings 112 and 14 mentioned above
The crystal layer of Ta+-y8ey contains selenium (
After forming each crystal layer on the substrate, the rounded crystal itself containing 8e) is brittle and easily cracks.
Particularly, the substrate 11 and the active layer 13 have the drawback that when a chip for forming a laser element is taken out by a rifling process, the mirror surface is not pierced and cracks occur in the grown large crystal layer. Cracks tend to occur in the sandwiched 9 cladding layer. This is because the cladding layer 12 is sandwiched between crystals of different compositions, so when force is applied to the crystals to open them, strain occurs in the cladding layer 120. The object of the present invention is to provide an infrared laser device that eliminates the above-mentioned drawbacks. In an infrared laser element in which crystal layers are sequentially laminated on a compound conductor substrate, and the upper and lower portions of the crystal layer serving as a region for laser emission are formed with crystal layers having a composition different from that of the crystal layer, the crystal layer serving as the region for laser emission. The lattice constant of the upper crystal layer is made to match the lattice constant of the crystal layer of the Rade emission region.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a sectional view showing the structure of the infrared radar element of the present invention, and FIG. 4 is a sectional view of the apparatus used to form the sheet element.

As shown in FIG. 3, the Rade element of the present invention is a P-type PbT
, on the substrate 21 is a P-type Pb+-z8nzTa crystal layer as the first cladding layer 22, and on top of that is a P-type Pb+-z8nzTa nanocrystal layer 22.
A Pb-type Pb-x8nxTe crystal layer is formed as an active layer 23, and a KdN-type PbTe+-y8ey crystal layer is formed as a second cladding layer 24 by liquid phase epitaxy.

In order to form such a laser element, a liquid phase epitaxial growth apparatus as shown in FIG. 4 is used, which comprises a slide member 31 made of carbon and a support stand 32. That is, a P-type PbTe substrate doped with Tariq A (Tj) and a dummy PbTe thin plate were embedded in the support base, and a 35KtiP type Pbt-x8nxT6 material was embedded in the liquid reservoir provided on the slide member. , PIPbt-x8nxTe materials with different KtiX values were added to the liquid reservoir 3.
7tlN-type PbTat-y8ey materials were respectively filled, the apparatus was introduced into a reaction tube in a hydrogen gas atmosphere, and the reaction tube was heated at a temperature of about 500°C.

Thereafter, the slide member 31 is moved in the direction of arrow A while lowering the temperature, and the liquid reservoir is left still on the dummy thin plate to saturate the wI phase of Pb1-z8nxTe in the liquid reservoir with the components of the dummy thin plate. Thereafter, the slide member is further moved in the direction indicated by the arrow, and the liquid reservoir 35 is placed on the substrate to form a KP type Pb5-18nxTe crystal layer on the substrate as a first cladding layer. After that, the slide member is further moved in the arrow direction KM, and the liquid reservoir is placed on the substrate to form a crystalline active layer of KP type Pb5-x8nXT on the substrate. Move the slide member in the direction of arrow A to form an active layer like a puddle of Pb.
'-! Only the top of the 8nxTe crystal layer is PbTet-y
Since it is formed of a crystal layer of GEY, there are almost no cracks that occur when the crystal is opened as in the past, and the yield is improved when opening the crystal after epitaxial growth to extract chips. do.

The region that emits Radical light in the active layer region is the second region above it.
Since it is near the P-N junction interface with the cladding layer, if only the second cladding layer is lattice matched with the active layer, lattice defects will not be formed near the interface, resulting in a decrease in laser emission efficiency. There's nothing to do.

As described below, the structure of the infrared radar element of the present invention has the advantage that the yield of manufacturing chips for forming the element can be improved and a low-cost infrared radar element can be obtained.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the structure of a conventional infrared radar device, FIG. 3 is a diagram showing the structure of an infrared laser device according to the present invention, and FIG. 4 is a diagram showing the structure of an infrared laser device according to the present invention. FIG. In the figure, 1.11.21.33 is a PbT substrate, 2
゜12.22ti first oy'py layer, 3, 13.2.
"lH active layer 4.14.24 is the second cladding layer, 5.
6 is the crystal interface, 31 is the slide member, 32 is the support base, A is the dummy thin plate, 35, 36, 37 is the liquid reservoir, and M is the arrow indicating the sliding direction.

Claims (1)

[Claims] (υ Infrared rays produced by sequentially laminating crystal layers on a compound eyelid conductor base including a vessel, and forming upper and lower portions of the crystal layer, which becomes the laser emission region, with crystal layers having a composition different from that of the crystal layer. An infrared radar element characterized in that, in the laser probe, only the lattice constant of the crystal layer above the crystal layer serving as the radar emission region matches the 5-character constant of the crystal layer in the radar emission region. (2 ) The crystal layer that becomes the Rade emission region is made of Pb s
-x8nXT6, and the crystal layer located on the substrate side of the crystal layer is composed of Pb1-x8nxTe of the same conductivity type with a different composition number XO, and further the crystal layer located above the crystal layer that becomes the Rade emission region is composed of PbTsx-y8.y of opposite conductivity type, so that the lattice constants match only between the crystal layers on the p-n junction surface side. Infrared radar element.