JPS60233879A - Manufacture of semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To contrive the reduction of internal strain generating by impurity doping by a method wherein the growing temperature is restricted to a specific range of temperature in growing an Si-doped GaAs active layer on a GaAs substrate. CONSTITUTION:An n type AlGaAs layer 2 is grown on an n type GaAs substrate 1, and the Si-doped GaAs active layer 3 is grown on this layer 2 at a temperature within a range of 840-940 deg.C. Thereafter, a p type AlGaAs layer 4 is grown on the layer 3. This layer 3 is doped with Si at a high concentration in order to obtain a desired band of infrared wavelength. However, the doping of high concentration impurities into a semiconductor region produces strains in a crystal lattice on account of the difference in size between the atom constituting the mother crystal and the impurity atom. A growing temperature of 840-940 deg.C can be used as a condition for the epitaxial growth of high concentration SiGa in order to inhibit said strain.

Description

[Detailed description of the invention] (Technical field of invention) The present invention relates to a method for manufacturing an infrared semiconductor light emitting device.

(Description of Background Art) Many infrared semiconductor light emitting devices including light emitting diodes and semiconductor laser diodes have been proposed. In forming these infrared light emitting devices, there is a method of using GaAs doped with impurities at a high concentration as an active region. Such a high concentration impurity semiconductor is a so-called degenerate semiconductor and does not cause band edge absorption at one emission wavelength, so high external quantum efficiency can be expected and it also prevents optical edge damage (catastrophic degr.) of the laser diode.
It is also effective in preventing adduction.

(Problems to be Solved) However, doping a semiconductor region with impurities at a high concentration causes distortion in the crystal lattice due to the difference in size between the atoms constituting the host crystal and the impurity atoms. This strain causes potential fluctuations and local electric fields (References: rPhysical Review BJvol,
213 No. 2 (1884), p. 802-p. 807), these fluctuations and the local electric field can be reduced by applying an external electric field to a local electric field at the atomic size level. Since concentration and localization of the electron energy level occur, it has the disadvantage of deteriorating the device life and internal luminous efficiency.

(Objective of the Invention) An object of the present invention is to provide a method for manufacturing a semiconductor light emitting device that can reduce internal strain caused by impurity doping in a highly doped semiconductor.

(Means to solve the problem) In order to achieve this objective, in this i-mechanical method, the growth of a highly-concentrated impurity semiconductor layer forming one light-emitting element is carried out under conditions that suppress the internal strain due to impurity doping. The gist is what to do.

Therefore, in the present invention, when manufacturing a semiconductor light emitting device by growing a Si-doped Ga1g active layer on the upper side of a GaAs substrate, the Si-doped GaAs active layer is grown at a temperature of 840 to 840°C using a liquid phase epitaxial growth method. It is characterized by growing within a range.

(Function) When the Si-doped GaAs active layer is grown by liquid phase epitaxial growth in such a growth temperature range, it is possible to make the coordination distribution of Si as uniform as possible, thereby reducing internal stress. I can do it.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows the liquid phase epitaxial growth temperature (horizontal axis) and the vertical optical (LO) phonon mode (
2 is a characteristic curve diagram showing the relationship between the vertical axis) and the corresponding internal stress, and FIG. be. In this sectional view, hatching representing the cross section is omitted except for a portion.

In Figure 2, l is an n-type GaAs substrate, 2 is an n-type Al
A first cladding layer made of a lGaAs layer, 3 a GaAs active layer, 4 a second cladding layer made of a p-type AQGaAs layer, and 5 and 6 ohmic electrodes.

This GaAs active layer 3 is heavily doped with Si in order to obtain a desired infrared wavelength range. As described above, this doping causes internal strain, that is, strain in the lattice of the GaAs crystal.

On the other hand, St behaves as an ambipolar impurity in GaAs. In other words, Si can be coordinated to Ga-lattice points and As-lattice points, and each behaves electrically as a lattice point or an acceptor. It is known that the distribution is mainly proportional to the growth temperature in the liquid phase epitaxial growth method normally used to form semiconductor lasers (Reference: rJo
Urnal of Physics & Chemist
ry of 5olidtJ vol, 38 pp 1
041~1053゜(18?5), Mouth, J, Ashe
n et al.). The magnitude of lattice strain is determined by the distribution of this Si coordination. This distortion reflects the vertical optical vibration in the lattice vibration (
LO) can be determined from the half-width of the phonon. That is, this half-width reflects the strain applied to the grid.

Therefore, by examining the relationship between the half-width of this vertical optical phonon mode and the liquid phase epitaxial growth temperature, it is possible to know the temperature dependence of changes in the generated strain, and from this relationship, the growth temperature range in which the generation of strain can be reduced can be determined. I can do it.

Therefore, the inventors of this application changed the concentration of Si doped into GaAs from the latter half of 10 c-3 to 10 c-3.
For the first half of Layer-3, particularly for the ~10c layer-3, changes in internal strain caused by coordination of Si were evaluated by Raman scattering spectroscopy. The experimental results are shown in the characteristic curve diagram of FIG. 1 by characteristic curves ■ and I. In FIG. 1, the vertical axis on the left shows the half-value width of the vertical optical phonon mode appearing in the Raman scattering spectrum, and the vertical axis on the right shows the corresponding internal stress in relation to the growth temperature.

From this experimental result, as is clear from the characteristic curve I, the strain decreases as the growth temperature increases up to about 880°C, and as the growth temperature further increases, it is clear from the characteristic curve As such, there is a tendency for the number to increase again.

By the way, the half-width of the LO phonon in GaAs that does not contain impurities is 4 cm-'', and the spread of the half-width is 1c.
m-” is the magnitude of externally applied stress 0.113X
Corresponds to 109dyn/c+w2. Therefore, from the characteristic curves I and I according to the above experimental results, it is clear that Si-doped Ga
In As, the internal stress at 800°C is 0.7X
109dyn/cm2 Te, 0.5X at 840℃
109dynlCII2, and then the internal stress further decreases as the temperature rises, and as the temperature rises, the stress starts to increase again and becomes 0.5Xl09 at 940°C.
It can be seen that dyn/cl12.

Generally, the internal stress resulting from a heterojunction is approximately 108d7
Since this value is approximately n/c 2, it is necessary to suppress the internal stress to a value equal to or less than this value when considering the influence on one light emitting element.

Therefore, in order to satisfy this condition, in the method according to the present invention, 840% Si-doped GaAs is grown using the liquid phase epitaxial growth method.
A growth temperature range of ~840°C may be used.

As already explained, the internal stress reduction method shown here is carried out by making the distribution of coordination between the Ga-lattice points and the As-lattice points of Si as uniform as possible, and also by adjusting this distribution ratio. is determined by the growth temperature, so 5iil1
This distribution ratio is preserved even if the temperature is other than 10"cm-3. Therefore, when growing Si-doped GaAs by liquid phase epitaxial growth, the growth temperature range is 840-840cm-3.
If it is set to about 40'0, such distortion can be reduced.

Next, a manufacturing example of the AQ GaAa/GaAs double hetero laser diode shown in FIG. 2 will be briefly described. First, using liquid phase epitaxial growth method, n-type Ga
An n-type N)GaAs layer is grown on the Ag substrate 1 to serve as the first cladding layer 2, and then Si-doped is formed on the first cladding layer 2 at an appropriate temperature in the temperature range of 840 to 880°C. A GaAs active layer 3 is grown, and then a p-type AQGaAs layer is grown as a second cladding layer 4 on this active layer 3. Finally, P-side and n-side ohmic electrodes 5 and 6 are deposited to obtain this laser diode.

In this case, the growth temperature range was 840-880°C,
In this temperature range, Si behaves as a p-type impurity, and a p-type GaAs active layer 3 is obtained. On the other hand, if this growth temperature range is 880 to 940°C, n-type Ga
An Ag active layer can be obtained. Therefore, liquid phase epitaxial growth of Si-doped GaAs may be performed at an appropriate temperature within the temperature range of 840-840° C. as required.

In addition, in the above-mentioned example, the concentration of doped Si is ~
10I910l9, which is 1G”cm-3 (7
) can be selected within the range from the latter half to the first half of 10"cm-3.

Further, in the above embodiments, the method of the present invention is applied to a tuple heterojunction laser diode, but it is clear that the method of the present invention can also be applied to other light emitting devices, such as bipolar diodes. be. In that case, Si is grown on the GaAs substrate under the above-mentioned growth conditions.
After growing a doped GaAs active layer and then growing an AQGaAs layer of the opposite conductivity type on the active layer, the required electrodes may be deposited.

Furthermore, other conditions for manufacturing this semiconductor light emitting device may be set to any suitable conditions suitable for the device to be manufactured.

(Effects of the Invention) As is clear from the above description, when doping Si into GaAs when manufacturing a semiconductor light emitting device,
By limiting the growth temperature, internal strain caused by doping can be reduced. This makes it possible to suppress electric field concentration at the atomic size level and localization of electron energy levels caused by lattice distortion, making it possible to easily create highly efficient and long-life semiconductor light-emitting devices.
It can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 serves to explain a method for manufacturing a semiconductor light emitting device of the present invention. The liquid phase epitaxial growth temperature ('0) of Si-doped GaAs and the half value of the vertical optical phonon line (cm-
) width and the corresponding internal stress (109dyn
/c■2) Characteristic curve diagram showing the relationship. FIG. 2 is a line sectional view showing an example of a double hetero semiconductor laser manufactured by the method for manufacturing a semiconductor light emitting device of the present invention. ! ...GaAs substrate, 2...first cladding layer (n-type AQGaAs layer) 3.
・・GaAs active layer (Si-doped GaA+active layer) 4・
・Second kraft layer (P-type Al) GaAs layer) 5.6・
...Ohmic electrode. ``, Tsuzuki JJ, F J) July 22, 1980 2 Title of patent 1 (Conductor light emitting device - manufacturing method 3 Relation to the case of person making amendments Patent applicant address (〒-105) Port of Tokyo 1-7-12, Toranomon, Ward Name (o29) Oki Electric Industry Co., Ltd. Representative Nankai Hashimoto 4 Agent 170-5563 Address 905 Ikebukuro White House Building, 1-20-5 Higashiikebukuro, Toyoshima-ku, Tokyo In the Detailed Description of the Invention column, Brief Description of the Drawings and Figure 2 (1) of the Specification, page 1, line 17 of the specification, ``Formation of a light-emitting element f-'' has been changed to ``Light-emitting element f-''. Correct A to form the element f. (2), same, page 2, line 3, 1 [atastrophic
Il'GataStro DegradationJ
phic 0ptical degradation,
Correct it as l. (3), page 3, line 15, rsi configuration” as ff5i
``coordination to Ga and As lattice positions''. (4), page 3, line 16
"to equalize and equalize." (5), page 4, lines 2-3 [(horizontal axis) and...
(6) Same, page 7, line 9, ``Invented by'' is corrected to ``J by invention of r''. (,?), same, 10i, line 11 “Half 414 Ccm-
') %iJ ヲF potato price range (cm-riJ) (8) Correct 1 drawing, Figure 2, as shown in the attached correction diagram. Muna 1 import

Claims (1)

[Claims] When manufacturing a semiconductor light emitting device by growing a Si-doped GaAs active layer on the upper side of a GaAs substrate, the Si-doped GaAs active layer is grown at a temperature range of 840 to 940°C using a liquid phase epitaxial growth method. A method for manufacturing a semiconductor light emitting device characterized by: