JPS5821887A - Semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To perform a light intensity and high speed modulation by providing a semiconductor laser which has high specific resistance at both terminal on a substrate and an insular impurity region as a current path, forming an FET in parallel with the laser and driving a control electrode with reverse bias. CONSTITUTION:Semiconductor layers 2-6 forming a laser element are laminated on a semiconductor substrate 1, and an FET which has a channel region 8 and insular impurity regions 9, 9', 10 is provided on the layer 6 in parallel with each other. Since the control electrode 12 is used with reverse bias, almost no current is consumed. Thus, the light intensity can be modulated with a voltage pulse. The modulation velocity depends upon the responding velocity of the FET and the modulation velocity of the laser, thereby providing high speed modulation. Further, the layers 2, 6 are in high specific resistance, and a current path is formed in the region 10. In this manner, a laser oscillator flow a current only at the section which performs only the laser oscillation, thereby reducing the threshold current of the laser oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor light emitting device having a novel structure in which modulation of a semiconductor laser device can be performed directly through a high impedance input terminal.

Generally, modulation of a semiconductor laser device is performed by applying a current pulse of 10 to 100 mA directly to the laser device. The present invention connects a field effect transistor section (hereinafter abbreviated as FET section) to one electrode of a semiconductor laser element,
This is a semiconductor light emitting device formed monolithically.

FIG. 1 shows a cross-sectional view of a typical semiconductor light emitting collector of the present invention. A cross section perpendicular to the traveling direction of the laser beam is shown.

A semiconductor laser ice part is formed on the upper part of the semiconductor substrate 1 for growth, and PET is further formed in a fifth half (sixth semiconductor layer provided on the body layer, in parallel with the semiconductor laser part). Ru.

The semiconductor layer 2 41 is a high resistivity layer. The second semiconductor layer 3 becomes the cladding J of @1 of the semiconductor laser electron, the third semiconductor layer 4 becomes the active layer, and the fourth semiconductor layer 5 becomes the second cladding layer. Naturally, the second and fourth semiconductor layers have relatively smaller refractive indexes than the third semiconductor layer. And they have mutually opposite conductivity types. Furthermore, second and fourth semiconductors j-
is a semiconductor layer with a relatively large forbidden band width compared to the third semiconductor layer.

The fifth half-body layer 6 is a high resistivity layer.

8 is an impurity region forming a channel region. 9°9' and 10 are island-shaped impurity regions, each of which constitutes a source, a drain, and a current path to the semiconductor laser.

14 and 17 are a p-side electrode and an n-side electrode, respectively, of the semiconductor laser element. 13, 12, and 11 are each F
These are the drain electrode, gate electrode, and source electrode of the ET. In this case, 14, 13 degrees 11 and 17 are ohmic poles, and 12 is a Schottky pole.

The metal electrode 14 is an electrode of a semiconductor laser element.
, are short-circuited to the drain electrode 13 of the FET.

For example, the cross section perpendicular to the traveling direction of the laser beam is as follows: 1. A reflective surface is formed by an r-opening, and an optical resonator is configured.

By applying a voltage between the electrodes 11 and 17 of the semiconductor light emitting device having the above structure, it is possible to cause laser oscillation. An example of an equivalent circuit of this configuration is shown in FIG. The numbers in FIG. 2 correspond to the numbered parts in FIG. 8. D and G correspond to the source, drain, and gate of each FET.

Therefore, by applying voltages for 1B1'' to the gate 71112, the oscillation of the semiconductor laser can be controlled. Of course, a semiconductor light emitting device may also be constructed using a semiconductor layer having the opposite 2x electric type. Naturally, the isometric circuit also has opposite polarity.

The structure in which the oscillation of the semiconductor laser element can be controlled using the control polarity as described above produces the following advantages.

(1) Light intensity can be modulated by voltage pulses.

Since the electrode for 1Illm is used with reverse bias, almost no current is consumed. For this reason, ordinary silicon IC
, yc For example, TTL circuit (transistortra
It is possible to turn the semiconductor laser element ON-OFF using the output signal of the nsistor logic C1rcujt.

(2) Speed modulation is possible.

The modulation speed is determined by the response speed of the FET section and the modulation speed of the laser, and a modulation speed of %IGb/8 or more can be achieved.

Further, in the present invention, the current of the laser oscillation section is limited on both the n side and the p side with respect to the active layer. That is, one method is to make the first semiconductor layer 2 high in resistivity and provide the openings 15. The other may be the fifth semiconductor. It can be reduced to about 1/10 compared to the case without such means. Furthermore, the temperature characteristics can also be improved.

crystal, the first semiconductor layer is Ga, AlfAS (Qx<0
．． 7), the second semiconductor layer is Gar-yAtyAs
(0,2<)'<0.7), the third semiconductor layer is Gat-
The semiconductor layer of sg4 is GaI-sA4 As(0,2<S<0.71
, the fifth semiconductor layer has Ga1-tAttAst (O<1
<0.3), (where z:) y.

z)s, t)s).

3 to 6 are device cross-sectional views showing each step of the manufacturing process of the semiconductor light emitting device of the present invention.

Moreover, the above-mentioned FIG. 1 is a completed diagram.

The following layers are formed on one surface of an n-type GaAs substrate (electron concentration gn: 1018/3) having a (100) crystal on the upper surface by a well-known liquid phase epitaxial method.

Ga-Al-AS melt (7j For example, Ga:At=0
．． 7:0.3) in a hydrogen atmosphere at 830 to 870 C for about 3 hours, a GaAtA 8 layer 2 is formed on the GaA 3 substrate by a liquid phase epitaxial method. The specific resistance of this layer should be 500Ω·α or more. In practice, it is not necessary to exceed a specific resistance of about IOKΩ·crn. The thickness of the resistive layer needs to be 500 Å or more. It should not have a thickness of 1 μm or more. If this layer is thick, it will be difficult to process in the next process.

Next, striped grooves 15 are formed in this semiconductor substrate in parallel to the traveling direction of the laser beam. The etching solution for forming this groove is a mixed solution of phosphoric acid, hydrogen peroxide and ethylene glycol (volume: 1:1:3). Using conventional photolithography techniques is sufficient. Since this grooved GaAl-A3 layer 2 has a high resistivity, it plays the role of concentrating the current in the opening. It is also used to control the transverse mode by utilizing the seepage of laser light into the substrate.

- The second semiconductor layer 3 is p-type Gap, ? Ato,s
The thickness of the A3 layer is 318 m, and the third semiconductor layer 4 is made of GaAS.
The fourth semiconductor layer 5 is made of n-type Ga.
1),? AlosA 8 layers with a thickness of 1 μm, the fifth f
The four-body layer 6 is formed by continuously growing a resistivity GaAS layer to a thickness of 1 μm by liquid phase epitaxial growth. The specific resistance may be about the same as that of the semiconductor layer 2 described above. The region 20 corresponding to the laser oscillation part of the semiconductor layer 6 was treated with a mixture of sulfuric acid, peroxide/water solution, and water in a ratio of 4:1.
Etched at 1 (wood grain ratio) to a thickness of 0.3 μm. At this time, as an etching mask, a 0.5 μm thick s
Io, using a membrane.

Next, a negative type photoresist is applied to a thickness of 0.5 μm, and light is irradiated to areas other than those corresponding to the electrode portions 10 and 9 (9'). After development processing, S40. By etching the parts corresponding to 10 and 9 (9'),
? i-product is exposed. Since the photoresist is exposed to light on a flat part of the crystal plane, it is performed with high precision. Then, the S1 ions were dosed 2X at a voltage of 150kV.
N+ regions of 10 and 9 (9') are formed by a well-known ion implantation method in which ions are implanted at 1015 cm intervals. As for the ion implantation method itself, a normal method may be used. Area 1
0 is formed so as to be commercially connected to the semiconductor layer 5.

Furthermore, using exactly the same method, eight nnn impurity regions are formed by ion implantation. Si ions are implanted at 120 kV and at a dose of I x 10''tyn-2.

An S + 01 film is formed as an insulating layer 7 over the entire surface of the semi-solid substrate. Holes are formed in the insulating layer 7 at least in the portions corresponding to the electrode portions 11, 12.13 and 1''-'' aperture 14 using the IJ sogelaf technique.11.13 is an AU
Ohmic electrode using Ge N1 alloy.

Calculation 2 is Cr, 'l"i and Au each / r300 people.

This is a Schottky electrode formed by laminating layers to a thickness of 4,000 and 4,000. The drain electrode 13 of the FET and the electrode part of the laser are short-circuited by a wiring 14 made of Au0e-Ni.

After polishing the back surface of the semiconductor substrate 1 and etching it in the morning, Cr, Ti and Au were each etched at 300 A.

The p-side electrode 17 was evaporated to a thickness of 300 μm and 0.18 μm.
Nasu.

Finally, the crystal plane is folded in a plane perpendicular to the traveling direction of the laser beam to form an optical resonator. The laser length was 300 μm.

In this way, a semiconductor light emitting device is completed.

This light emitting element has a source electrode 11 and a laser probe n 11
Laser oscillation can be performed by applying a voltage of 4 to 5 V between the poles 17.The heating wavelength is 83 mm, and the threshold current is approximately 5 Ill A.
.

Modulation could be achieved up to 2.50 HZ. Also, the transconductance (gm) id of F'ET, 10m5 (
Millisiemens).

Of course, the present invention is not limited to the semiconductor materials shown in the examples. Although there are various means for mode stabilization of a semiconductor laser, it goes without saying that these methods may be applied to the solid state laser section of the light-emitting semi-enveloped device of the present invention, and are within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the semiconductor light emitting device of the present invention, taken in a plane perpendicular to and parallel to the traveling direction of the laser beam, FIG. 2 is an equivalent circuit of the semiconductor light emitting device, and FIGS. FIG. 2 is a cross-sectional view of a semiconductor light emitting device according to the present invention for explaining the manufacturing process of the semiconductor light emitting device according to the present invention. ;1-p('T a S substrate, 2... high resistivity GaAS layer, 3.5... Ga AtA S layer, 4...
・Active layer, 6... High resistivity GaAs layer, 11... Source electrode, 13... Drain electrode, 12... Gate electrode, 14... Laser emitting part p side's electrode, 17...
n-side electrode. Patent applicant Makoto Ishiita, Director of the Agency of Industrial Science and Technology (11) ¥, Il Figure Punishment Z Sen

Claims (1)

[Claims] 1. A first . Second. Third. Fourth and fifth semiconductor layers are sequentially stacked, and p-n
A stacked region of semiconductor layers having a junction, a field effect transistor portion having a gate electrode and a first blind electrode sandwiching the gate electrode, a pole and a second electrode are formed at least M, and The semiconductor layer has a softer refractive index than the third semiconductor layer, and has a relatively small refractive index. '' are semiconductor layers having a relatively large band width and mutually opposite conductivity types, and the first semiconductor layer is a high resistivity layer and is parallel to the traveling direction of the laser beam, and at least the semiconductor layer 4WL, the fifth semiconductor layer is a high resistivity layer, and a stripe-shaped impurity is formed inside the striped groove at a position approximately corresponding to the striped groove in the same direction as the groove. The 8g1 electrode of the field effect transistor, which is connected to the striped impurity region in an air-like manner and allows current to flow therein, is short-circuited to cause radiation to flow in the longitudinal direction of the striped groove and the impurity region. 1. A semiconductor light emitting device characterized by having at least a means serving as an optical resonator for emitting light. 2. The semiconductor light emitting device according to claim 1, wherein the field effect transistor portion is formed in an impurity region provided in the fifth semiconductor layer.