JPS58128784A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To operate a LED stably by bringing a semiconductor layer as an active layer to low carrier concentration while forming a semiconductor layer as a buried layer having a refractive index lower than the former semiconductor layer and an energy band gap larger than it. CONSTITUTION:A first semiconductor layer 2 has a first clad layer having first conduction type. The second semiconductor layer 3 as the active layer forming a first hetero-junction in striped shape is formed onto the layer 2. A third semiconductor layer 4 as a second clad layer having second conduction type reverse to the first conduction type shaping a second hetero-junction is formed onto the layer 3. The layer 3 has the low carrier concentration of 10<15>atom/cm<-3> or less while the semiconductor layer 12 as the buried layer having the refractive index lower than the layer 3 and the energy band gap larger than the layer 3 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to semiconductor light emitting devices such as semiconductor lasers and semiconductor light emitting diodes.

As such a semiconductor light emitting device, one having the following configuration has been proposed.

As shown in FIG. 1, for example, on an N-type semiconductor substrate 1 made of InP, a
2, a semiconductor layer 3 as an active layer made of QainAsP element system, an N type semiconductor 4 as another cladding layer made of InP, and an electrode attachment layer (gap layer) made of GajnAspJ element system. ) are sequentially stacked in this order. In this case, the semiconductor layer 2 is formed in a mesa shape so that its surface facing the semiconductor layer 3 extends in a striped pattern (in the direction perpendicular to the plane of the paper), and the semiconductor layer 2 is laminated with semiconductors 3.4 and 5. The body is formed in an inverted meridian shape so that the semiconductor layer 3 extends with a striped pattern that is exactly the same as the striped pattern on the surface of the semiconductor 2 on the semiconductor 3 side.

Thus, the semiconductor layers 2, 3, 4, and 5 are buried with the semiconductor layer 6 as a buried layer. In this case, semiconductor ■6 is
In on the semiconductor substrate 1 side in contact with the side surfaces of the semiconductor layers 2 and 3
A P-type semiconductor ■7 consisting of P and a semiconductor l! The side opposite to the semiconductor substrate 1 side where the side surfaces of 4 and 5 are in contact and the surface opposite to the semiconductor substrate 1 side is on the same plane as the surface of the semiconductor layer 5 on the opposite side to the semiconductor substrate 1 side. An electrode 9 made of, for example, Au-Ge-Ni is attached to the semiconductor 11 on the surface opposite to the semiconductor layer 2II, and the semiconductor of the semiconductor layer 6 is For example, silicon oxide 10 is formed on the surface opposite to the substrate 1 side, and an electrode similar to the electrode 9 is formed on the semiconductor layer 5 on the surface opposite to the semiconductor layer 4 side. has been done.

Further, at least at both ends of the striped pattern of the semiconductor layer 3 serving as the active layer in the extending direction, reflective surfaces (not shown) of Faprepe O-, which are parallel to each other and perpendicular to the extending direction of the striped pattern, are formed. ing.

The above is the configuration of the semiconductor light emitting device according to the conventional rules.
1. If a bias power supply with the electrode 11 side positive is connected to the dark side, a current flows from the electrode 11 side to the electrode 9 side via the semiconductor II3, the semiconductors 112.4 and 5, and the semiconductor substrate 1. Based on this, light emission is obtained in the semiconductor 113. In this case, no current flows through the semiconductor layer 6 since it has a PN junction of opposite polarity to the bias power supply of the semiconductor layers 7 and 8. Furthermore, if light emission is obtained in the semiconductor layer 3, since the semiconductor layers 3, 4 and 6 have a lower refractive index than the semiconductor layer 3, the light based on the light emission will be confined within the semiconductor layer 3. The light propagates, is reflected at the reflective surface of the 7th abbellum of the semiconductor layer 3, and the same process is repeated. As a result, laser oscillation is obtained, and based on the laser oscillation, laser light is emitted to the outside via the reflective surface of the fiber bellows.

Therefore, the semiconductor light emitting device shown in FIG. 1 functions as a semiconductor laser.

However, in the semiconductor light emitting device shown in FIG. 1 which functions as such a semiconductor laser, since the active semiconductor 3 has a striped pattern, current flows in a constricted manner.
Therefore, it is called a type 9 semiconductor light emitting device. Further, since the semiconductor layer 3 as an active layer having a striped pattern is buried in the semiconductor layer 6, the buried/electrode 1#? This is called a type.

For this reason, the 11th! The semiconductor light emitting device shown in FIG. 1 is characterized in that it can obtain laser oscillation with a relatively small current value and therefore has a low oscillation threshold.

However, in the case of the conventional semiconductor light emitting device shown in FIG.
Moreover, it is necessary to control the thickness of the semiconductor (7) so that it does not come into contact with the side surface of the semiconductor (4) serving as the cladding (4) having the same conductivity type as that of the semiconductor (7). It has the disadvantage that it is difficult to obtain.

Also, the semiconductor 7 which constitutes the semiconductor layer 6 as the buried 11I
Since semiconductor layers 7 and 8 are required to have opposite conductivity types and a relatively high carrier concentration, these semiconductor layers 7 and 8 are formed by a liquid layer growth method after the formation of semiconductor layer 3. Therefore, when forming the semiconductor layer 7, the semiconductor 11
3 melts back, resulting in a semiconductor lI3 that does not have the expected width, resulting in a disadvantage that the desired characteristics cannot be obtained.

Further, since the semiconductor layer 6 has a semiconductor layer 7 in contact with the side surface of the semiconductor layer 3, and the semiconductor layer 7 has a relatively high carrier concentration, the leakage current passing through the semiconductor layer 7 is relatively large. However, the oscillation threshold has temperature dependence, and stable operation cannot be obtained.

Therefore, the present invention is a complete plan for semiconductor light emission ii*tiii without the above-mentioned drawbacks, which will become clear from the detailed description below.

'l82WIIu Shows an example of a semiconductor light emitting device according to the present invention, and the same reference numerals are used for parts corresponding to 11111.
H*ukoae omittedti is also misgcrIn the above-mentioned configuration, the semiconductor ■6 as the layer polishing is 1d'at
omicila, which has a low carrier concentration of 1 (f'ato ■/C♂ or less), a lower refractive index than the semiconductor layer 3, and a larger energy band gap than the semiconductor layer 3. Therefore, with this stupid semiconductor -12, the semiconductor ■
It has the same configuration as the 11th I except that 3 is embedded.

The above is an example of the configuration of the semiconductor light emitting device according to the present invention.
The semiconductor 112 as a dielectric layer has the same potential as in the case of Il, while the semiconductor 112 as a dielectric layer can pass through the first II as it has a low carrier concentration below the 16' atom Zctrx, as well as to the electrodes 9 and 11-. When the bias Ill source is connected and a current flows through the semiconductor 3, no current flows as in the case of the semiconductor 6 shown in FIG. Also, since the semiconductor layer 1=2tj has a lower refractive index than the semiconductor layer 3 as an active layer, 1
, when light emission is obtained in the semiconductor layer 3, the light is transmitted to the semiconductor layer 3.
It is meant to be confined.

Therefore, the case of the semiconductor light emitting device according to the present invention shown in FIG. 2 is the same as the case of the semiconductor light emitting device shown in FIG. It functions as a semiconductor laser, and has the same features as the case described above with reference to FIG.

In the case of the semiconductor light emitting device according to the present invention shown in FIG.
There's no need.

Furthermore, since the semiconductor layer 12 has a low carrier concentration of 10f5atos/c- or less, the semiconductor layer 1
) 2 can be easily formed by vapor phase growth, and in this case there is no risk of damage to the semiconductor layer 3.

Moreover, since the semiconductor layer 12 has a low carrier concentration of 10 atoms/c or less, there is almost no leakage current through the semiconductor layer 12, or even if there is, it is negligible and the temperature is close to the oscillation threshold. No dependencies.

Further, since the semiconductor layer 12 has a larger energy band gap than the semiconductor layer 3, the light propagating to the semiconductor 3 will not be lost by the semiconductor 12.

Therefore, it has great features such as being able to obtain a semiconductor light emitting device that can operate stably and efficiently and has good characteristics with negligible leakage current.

Although the above description has been made regarding the case where the present invention is applied to a semiconductor laser, the point is that the first semiconductor layer as the first cladding (1) having the first conductivity type, and the first a second semiconductor layer as an active layer formed to form a first heterojunction in a stripe shape on the semiconductor layer of I2, and a second semiconductor layer formed to form a second heterojunction on the semiconductor-1 of I2; a second conductivity type opposite to the first conductivity type
It will be obvious that the present invention can be applied to various semiconductor light emitting devices comprising a third semiconductor I as a cladding layer.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a conventional semiconductor light emitting device. FIG. 2 is a schematic cross-sectional view showing an example of a semiconductor light emitting device according to the present invention. 1... Semiconductor substrate 2.4.
... Semiconductor as cladding layer ■3...
...... Semiconductor layer 5 as an active layer
...... Semiconductor layer 6.12 as an electrode attachment layer - Semiconductor layer 9.11 as a buried layer ... Electrode 10 ...・・・・・・・・・Insulating layer Ss C Wa%s cQ Procedural amendment (method) % formula% 1. Indication of incident 1982 Patent Application No. 11155 2. Name of invention Inner conductor light emitting device 3 , Relationship with the case of the person making the amendment Patent applicant 4, agent

Claims (1)

[Claims] a first semiconductor layer as a first cladding (1) having a first conductivity type;
A second semiconductor layer as an active layer formed to form a heterojunction, and a first conductivity type formed to form a second heterojunction on the second semiconductor layer. In a semiconductor light emitting device comprising a third semiconductor layer as a second cladding (1) having an opposite second conductivity type, the second semiconductor layer has a low carrier concentration of 1 o atom/c1'' or less. and embedded with a fourth semiconductor layer as a buried layer having a lower refractive index than the second semiconductor layer and a larger energy band gap than the second semiconductor layer. 1. A semiconductor light emitting device characterized by: