JPS6321283A - Liquid phase epitaxy - Google Patents

Abstract

PURPOSE:To grow a superlattice on a substrate by alternately distributing different growth solns. to plural soln. reservoirs with a lower opening having a width smaller than that of the substrate, and passing the substrate directly below each growth soln. at a fixed speed in the fixed direction. CONSTITUTION:Plural sliding soln. reservoirs 3 with the lower opening having a width smaller than that of the substrate 2 are provided on a slider 1 housing the substrate 2. Two kinds of growth solns. are separately charged into a free- to-slide distribution soln. reservoir 4 furnished on the soln. reservoir 3, and dissolved. Then the distribution soln. reservoir 4 is slid over the soln. reservoir 3 to charge one of the two kinds of growth solns. into the first, third, and fifth soln. reservoirs 7, and another growth soln. is charged into the second, fourth, and sixth soln. reservoirs 8. Subsequently, the slider 1 housing the sub strate 2 is slid at a fixed speed in the fixed direction to bring the substrate 2 into contact with the growth soln. in each soln. reservoir 3, and a superlattice is grown on the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid phase epitaxial growth method used for producing optical devices in the field of optoelectronics, such as semiconductor lasers used as light sources in optical communication systems.

31＼-/゛Conventional technology Recently, as semiconductor lasers used as light sources in optical communication systems have been put into practical use, advances in crystal growth technology have led to
Development of products with higher performance is progressing. For example, a semiconductor laser that uses a superlattice in which different types of crystals with a thickness of several nanometers to several nanometers are alternately laminated in the light emitting region is one example.
ll Iaser (hereinafter referred to as MQW laser). Because this MQW laser has a thin superlattice structure, it appeared as an application of new crystal growth techniques that can grow ultra-thin films, such as molecular beam epitaxy (MBE) and metal organic vapor phase epitaxy (MOVP). The liquid phase epitaxial growth method is the most common crystal growth method used to create semiconductor lasers, etc., but this growth method has a faster growth rate than the MBE method and MOCVD method, so it is difficult to grow a superlattice structure. However, liquid phase epitaxial growth has been considered to be unsuitable for the above-mentioned values.Compared to the above-mentioned two growth methods, liquid-phase epitaxial growth can obtain better quality crystals and is simpler, and in terms of materials, the GaAβA11l/GaAs system has the above-mentioned values. There are many reports on MQW lasers using two growth methods, but since the InGILASP/rnP system has not been completed, Sasai et al.
Attempting to grow lasers and obtaining good characteristics (Nati
onalTechnical Report Vol.
32 No. 2 Apr1986 255-26
1). To explain Sasai et al.'s method with reference to FIG. 5, 61 is a slider, 52 is an n-InP substrate, 53 is a solution reservoir, 54 is an n-InP growth solution, 551L, 55
1) is a non-doped InGaAsP barrier layer growth solution (
Wavelength 1.1 μm) 56 is non-doped InGaAs
P well layer growth solution (wavelength 1.3 pm), 57 is P-
The InP growth solution 58 is a P-In(raAsP growth solution.The n-InP substrate 62 is initially positioned to the left of the n-InP growth solution 54, and when the temperature reaches a predetermined temperature, the slider 61 is turned to the n-InP growth solution. -1nP substrate 52 is n-1
Growth is performed by sliding it so that it is directly under the nP growth solution 54. Next, non-doped I is grown as a superlattice structure.
The nGaAsP barrier layer growth solutions 65zL, 55b, and the 5-benon-doped InGaAsP well layer growth solution 56 are slid back and forth for the number of layers to be deposited. At this time, the slider "-51 does not stop once every time the n-InP substrate 62 comes directly under each growth solution, but slides continuously at a constant speed to increase the contact time between the substrate and the growth solution. We aim to shorten the growth time by reducing the number of layers.After the reciprocating slide is completed for the predetermined number of layers, the n-
The InP substrate is sequentially treated with P-InP growth solution 57 and P-
Growth is performed by sliding it directly under the InCaAsP growth solution 68.

In this method, when growing a superlattice structure, the growth time is shortened by continuous back-and-forth sliding, and the growth rate is also slowed down by lowering the growth temperature by approximately Iptso℃ compared to normal liquid phase epitaxial growth. . Based on the growth described above, Sasai et al. prototyped a BH tank structure MQW laser and obtained good characteristics.

Problems to be Solved by the Invention However, the above configuration has the following problems. In other words, continuous 6 bases as mentioned above.

In the second slide 8, a non-doped InGaAsP well layer (~
200 people), but it is not possible to make the non-doped InGaAsP well layer thin (~500 people). This is n −In
Although the P substrate 52 only passes directly under the non-doped InGaAsP well layer growth solution 66, the non-doped InGaAsP (
This is because the contact time becomes longer as the sliding direction is reversed directly under the raAsP barrier layer growth solutions 55a and 56b. The thickness of the barrier layer affects the injection efficiency of electrons into the well layer, and if the barrier layer is thick, the threshold current of the semiconductor laser cannot be lowered because the injection efficiency decreases. Furthermore, in the above-mentioned reciprocating slide, variations in composition are likely to occur due to the withdrawal of the growth solution.

The present invention eliminates the difficulty of thinning the barrier layer by reciprocating slides as described above, makes it possible to thin not only the barrier layer but also the well layer, and provides a liquid phase solution to obtain a superlattice structure with suppressed compositional variations. The purpose is to provide an epitaxial growth method.

Means for Solving Problems 7Peno The present invention comprises a slider for installing a substrate and a plurality of sliders for storing a growth solution that can be slid relative to the slider.
a solution reservoir having n through-holes; and two reservoirs disposed on the solution reservoir, slidable relative to the solution reservoir, and distributing the growth solution to the plurality of through-holes of the solution reservoir. a distribution solution reservoir having through-holes for accommodating a growth solution, the bottom openings of the two through-holes of the distribution solution reservoir being such that when the distribution solution reservoir slides over the solution reservoir, one is 1°3.
．． 6. . . . corresponds to the upper opening of the through hole of the n-th solution reservoir, and the other one corresponds to 2, 4, . .......

Using a boat, which corresponds to the upper opening of the (n-1)th through hole, and in which the width of the lower opening of each through hole of the solution reservoir in the sliding direction is smaller than the width of the substrate, After storing different types of growth solutions in the two through-holes and dissolving them uniformly, slide the distribution solution reservoir over the solution reservoir, and add one of the different types of growth solutions to 1.3, 5.・・・
..., the other one is inserted into the through hole of the n-th solution reservoir 2.4. After dispensing the solution into the through-hole of the (n-1)th solution reservoir, the slider on which the substrate is installed is continuously slid at a constant speed without stopping, so that the substrate is dispensed with the solution. The above object is achieved by growing a superlattice structure on a substrate by bringing it into contact with two different growth solutions alternately stored in through holes of a reservoir.

According to the above-mentioned structure, the present invention distributes two different growth solutions with uniform composition alternately to the through-holes of the solution reservoir, and flows under the through-hole of the solution reservoir whose width is smaller than the width of the substrate in the sliding direction. Since the substrate is slid at a constant speed in the direction, the contact time between the substrate and the growth solution, and thus the growth time, is shortened, and the growth of a superstructured structure with little draw-in of the growth solution and suppressed compositional variations is possible. It made it possible.

Embodiment FIG. 1 shows an embodiment of the present invention, in which InGaAs P/
FIG. 2 is a perspective view of a boat used for growing an InP-based MQW laser. In FIG. 1, 1 is a slider 9B, 3 is a solution reservoir, 4 is a distribution solution reservoir, and 5 is a non-doped In
GaAsP barrier layer growth solution (wavelength 1.1 μm), 6 is non-doped InGaAsP well layer growth solution (wavelength 1.3 μm)
7 is a barrier layer solution storage hole, 8 is a well layer solution storage hole, 10 is a P-InP growth solution, 11 is a P-InGa
Agp growth solution.

In order to further understand FIG. 1, using the cross-sectional view of FIG. 2, 2 is n-InP.
The substrate 9 is an n-InP growth solution.

The distribution solution reservoir containing the non-doped InGaAsP barrier layer growth solution 5 and the non-doped InGaAsP growth solution 6 can be slid with respect to the solution reservoir 3, and initially the two lower openings are through-holes containing the n-InP growth solution 9. and the upper opening of the leftmost barrier layer solution storage hole 7. Further, the slider 1 on which the n-InP substrate 2 is installed is slidable with respect to the solution reservoir 3, so that the n-InP substrate 2 is initially placed on the left side of the n-InP growth solution 9. The upper openings of the barrier layer solution storage holes 7 and the well layer solution storage holes 8 are arranged in left and right sections 10 and 10, as shown in FIG. This corresponds to the lower openings of the two through holes that housed the barrier layer solution and the well layer solution in the solution reservoir.

FIG. 3 is a sectional view taken along the line AA' in FIG. 2, showing the situation. To explain the growth procedure, first raise the temperature in the state shown in Figure 2, then keep it at a constant temperature to grow non-doped InGa.
AsP barrier layer growth solution 5 and non-doped InGaAs
The P well layer growth solution 6 is uniformly dissolved. Subsequently, the distribution solution reservoir 4 is slid on the solution reservoir 3 as shown by the arrow in FIG. 2 to distribute each growth solution to each growth solution storage hole 7.8 of the solution reservoir 3. This situation is shown in FIG. In this way, each of the distributed growth solutions 5/ and 6/ has a uniform composition, which saves time and effort compared to preparing the growth solutions by individually weighing them into each storage hole. Next, slide slider 1 as shown by the arrow in Figure 4 n-I
The nP substrate 2 is placed directly under the n-InP growth solution 9, and growth is performed for a predetermined period of time. Next, the n-InP substrate 2 is grown at a constant speed using a non-doped InGaAsP barrier layer growth solution 5' and a non-doped InGaAsP well layer growth solution 6.
' without stopping, slide it to just below the P -1nP growth solution 10, and grow for a predetermined time. Finally, the n-InP substrate 2 is moved directly under the P-InGaAsP growth solution and grown for a predetermined period of time to complete the series of growth.

In this example, the growth of the active region consisting of a superlattice structure of a non-doped InGaAsP barrier layer (wavelength: 1.1 μm)/non-doped InGaAsP well layer (wavelength: 1.3 μm) is performed in one direction at a constant speed, and then in the sliding direction. Since the width of the lower opening of each growth solution storage hole in the solution reservoir is narrower than the width of the substrate, the growth time can be further shortened compared to the method using the reciprocating slide described above. Since the slide is made in one direction, once the growth solution is drawn in in a reciprocating slide, the composition of the subsequent growth layer will vary, whereas even if some part of the growth solution is pulled in, there will be variations in the composition of the subsequent growth layer. It has no effect. When the barrier layer was grown using the above method, the width of the substrate was 10 m, the width of the lower opening of each barrier layer of the solution reservoir and the well layer storage hole was 3wn, and the slide speed was 50 mm/see. Good results were obtained for both the thickness of the well layer and the thickness of about 100λ. Furthermore, when a BH structure MQW laser having an active region of five barrier layer/well layer pairs was fabricated, a minimum threshold current of 10 mA was obtained. As described above, according to this embodiment, a superlattice structure in which both the barrier layer and the well layer are thinner than before can be obtained, and an MQW laser with good characteristics can be obtained.

Effects of the Invention As described above, the present invention alternately distributes different growth solutions with a uniform composition into the growth solution storage hole having a lower opening that is wider than the trench width than the substrate width in the slide direction. Because the substrate is passed directly beneath it in one direction at a constant speed, it is possible to create a thinner film than the conventional method using a reciprocating slide, and it is highly effective because it allows the growth of a superlattice structure with less variation in composition.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of a boat used in the liquid phase epitaxy layer growth method according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of the boat in Fig. 1, and Fig. 3 is an A of Fig. 2.
- A' cross-sectional view, Figure 4 is an explanatory diagram showing how the two growth solutions in the distribution solution reservoir are distributed alternately to the growth solution storage hole of the solution reservoir, and Figure 6 is an MQW laser using a conventional reciprocating slide. FIG. 1.61...Dan Sly f-12,52...n
-InP substrate, 3.63...solution reservoir, 4...
...Distribution solution reservoir, 5.5'...River, non-doped InG
aAsP barrier layer growth solution, 6.6'...Non-doped InGaAsP well layer growth solution, 7...
Barrier layer solution storage hole, 8...well layer solution storage hole.

Claims (2)

[Claims] (1) A slider for installing a substrate, a solution reservoir having a plurality of (n) through holes for storing a growth solution that can slide relative to the slider, and a solution reservoir located on the solution reservoir. 2 for dispensing the growth solution into the plurality of through-holes of the solution reservoir;
a distribution solution reservoir having through holes for accommodating two growth solutions, the bottom openings of the two through holes of the distribution solution reservoir comprising:
When the distribution solution reservoir slides on the solution reservoir, one of the plurality of through holes of the solution reservoir is 1, 3, 5, . . .
..., corresponds to the upper opening of the n-th through hole, and the other one
One is to use boats corresponding to the upper openings of the 2nd, 4th, . After storage and uniform dissolution, slide the distribution solution reservoir over the solution reservoir to distribute one of the different growth solutions 1, 3, 5,...
..., after distributing one other growth solution to the through-hole of the nth solution reservoir and the other growth solution to the through-hole of the 2nd, 4th, ..., (n-1)th solution reservoir. , the slider on which the substrates are installed is continuously slid at a constant speed without stopping, and the substrates are alternately stored in the through holes of the 1st, . . . , nth solution reservoirs. A liquid phase epitaxial growth method characterized by growing a superlattice structure on a substrate in contact with two different growth solutions. (2) The liquid phase epitaxial growth method according to claim (1), wherein the liquid phase epitaxial growth method is carried out using a boat in which the width of the through hole of the solution reservoir is smaller than the width of the substrate in the direction in which the slider is slid.