JPH08274374A - Semiconductor light emitting device - Google Patents

Abstract

(57) [Summary] (Modified) [Constitution] When a large number of semiconductor light emitting element arrays, for example, light sources for printers, are formed using island-shaped semiconductor layers, the island-shaped semiconductor layers are divided into a plurality of groups, and each group is divided into groups. Common electrodes 4a, 4 for each
b, ... are provided. Further, the individual electrodes of the elements having different common electrodes are collectively formed as an individual electrode 3. [Effect] Since the common electrode is divided into a plurality of parts, it is possible to form a plurality of common electrodes by using at least half the individual electrodes as in the above configuration without providing individual electrodes for all the elements as in the conventional case. It is possible to emit light by applying a voltage by selecting an arbitrary element by utilizing the combination of and. Therefore, the manufacturing process of such a light emitting element array, particularly the wire bonding process, is simplified, and the working efficiency is considerably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device,
In particular, the present invention relates to a semiconductor light emitting device used as an exposure source of a photosensitive drum for a page printer.

[0002]

2. Description of the Related Art A conventional semiconductor light emitting device is shown in FIGS.
Shown in FIG. 5 is a cross-sectional view taken along the line AA of FIG. 4 and 5, 21 is a substrate, 22 is an island-shaped semiconductor layer,
Reference numeral 23 is an individual electrode, and 24 is a common electrode.

The substrate 21 is made of, for example, a single crystal semiconductor substrate made of silicon (Si), gallium arsenide (GaAs), or the like.

The island-shaped semiconductor layer 22 is made of a compound semiconductor such as gallium arsenide or aluminum gallium arsenide, and is composed of a layer 22a containing an impurity of opposite conductivity type and a layer 22b containing an impurity of one conductivity type. A semiconductor junction is formed at the interface between the layer 22a containing impurities of opposite conductivity type and the layer 22b containing impurities of one conductivity type. The island-shaped semiconductor layer 22 is formed in an island shape after forming a single crystal semiconductor layer by, for example, the MOCVD method or the MBE method.

A protective film 25 made of, for example, a silicon nitride film is formed on the surface of the island-shaped semiconductor layer 22, and the surface of the protective film 25 is made of, for example, gold (Au).
An individual electrode 23 composed of, for example, is formed. The individual electrodes 23 extend from the upper surface portion of the layer 22a containing the impurity of the opposite conductivity type of the island-shaped semiconductor layer 22 to the neighboring island-shaped semiconductor layers 22 alternately through the wall surface portion to the vicinity of the end surface of the substrate 21. It is formed so as to extend. A common electrode 24 made of gold (Au) or the like is formed on almost the entire back surface of the substrate 21.

The island-shaped semiconductor layer 22, the individual electrodes 23, and the common electrode 24 form individual light emitting elements (light emitting diodes), which are formed on the substrate 21 in a line. In this case, for example, the individual electrode 23 serves as the anode electrode of the light emitting diode and the common electrode 24 serves as the cathode electrode. In addition, the individual electrode 23 is connected to an external circuit in its wide portion by a wire bonding method or the like.

In such a semiconductor light emitting device, as shown in FIG. 6, for example, when a current is passed in the forward direction from the individual electrode 23 toward the common electrode 24, electrons are generated in the layer 22a containing impurities of opposite conductivity type. The holes are injected into the layer 22b containing the impurities of the opposite conductivity type. Light is generated by the radiative recombination of some of these minority carriers with the majority carriers. Further, by selecting one of the light emitting elements formed in a row to emit light, the light emitting element is used, for example, as a light source for neutralizing a photosensitive drum for a page printer.

The common electrode 24 shown in FIG.
It may be provided on the one surface side.

[0009]

However, in this conventional semiconductor light emitting device, the semiconductor layer 22b containing an impurity of one conductivity type is connected via the substrate 21 to the common electrode 24 formed on the back surface side of the substrate 21. However, since the semiconductor layers 22a containing impurities of the opposite conductivity type are individually connected to the individual electrodes 23, when the light emitting element is made finer, the formation density of the individual electrodes 23 is also increased, and accordingly, the external electrodes are formed. There are problems that the number of connection points with the circuit increases and the workability of wire bonding deteriorates. Eg 30
If it is a semiconductor light emitting device of 0 dpi (dot per inch),
The array pitch of the island-shaped semiconductor layers 22 is 84.6 μm,
In the case of a semiconductor light emitting device of 600 dpi, the array pitch of the island-shaped semiconductor layers 22 is 42.3 μm, which is half that of 300 dpi, and the individual electrodes 23 have to be made narrower, which deteriorates the workability of wire bonding. There was a problem.

Further, if the number of individual electrodes 23 increases, the number of wire bonding locations increases correspondingly, and there is a problem that the wire bonding work takes a long time.

[0011]

SUMMARY OF THE INVENTION The present invention has been invented in view of the above problems of the prior art and solves the problem that the formation density of the individual electrodes connected to the light emitting element is increased and the wire bonding work is performed. An object of the present invention is to provide a semiconductor light emitting device that eliminates the need for a long time.

[0012]

In order to achieve the above object, according to the invention described in claim 1, an island-shaped semiconductor layer composed of a semiconductor layer of one conductivity type and a semiconductor layer of opposite conductivity type is provided on a substrate. In a semiconductor light emitting device in which a common electrode is connected to a semiconductor layer of one conductivity type and an individual electrode is connected to a semiconductor layer of an opposite conductivity type, the island-shaped semiconductor layer is divided into a plurality of groups, and A common electrode was provided, and the individual electrodes were provided for each of the plurality of island-shaped semiconductor layers belonging to different groups.

According to the second aspect of the invention, an island-shaped semiconductor layer composed of a semiconductor layer of one conductivity type and a semiconductor layer of the opposite conductivity type is provided on a substrate, and a common electrode is connected to the semiconductor layer of one conductivity type. In the semiconductor light emitting device provided with the individual electrodes connected to the opposite conductivity type semiconductor layer, the opposite conductivity type semiconductor layer is provided on the one conductivity type semiconductor layer in a smaller area than the one conductivity type semiconductor layer. A common electrode connected to a group of one conductivity type semiconductor layers was provided from above the one conductivity type semiconductor layer to above the substrate, and an individual electrode was provided from above the opposite conductivity type semiconductor layer above the substrate.

[0014]

In the semiconductor light emitting device described in the claims, the density of the individual electrodes connected to the light emitting element is reduced and the number of individual electrodes is reduced, so that the wire bonding work can be performed in a short time.

Further, in the semiconductor light emitting device according to the second aspect, the island-shaped semiconductor layer can be divided into a plurality of groups and connected to the common electrode, and the individual electrode is provided for each of the plurality of island-shaped semiconductor layers belonging to different groups. Will be able to.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 1 is a diagram showing an embodiment of a semiconductor light emitting device according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. 1 and 2, 1 is a substrate, 2 is an island-shaped semiconductor layer, 3 is an individual electrode, and 4 is a common electrode.

The substrate 1 is composed of, for example, a single crystal semiconductor substrate of silicon (Si), gallium arsenide (GaAs), or the like.

The island-shaped semiconductor layer 2 is composed of a compound semiconductor film such as gallium arsenide or aluminum gallium arsenide (GaAlAs) and contains a layer 2a containing impurities of opposite conductivity type and a layer 2b containing impurities of one conductivity type. A semiconductor junction is formed at the interface between the layer 2a containing impurities of opposite conductivity type and the layer 2b containing impurities of one conductivity type. The island-shaped semiconductor layer 2 is formed in an island shape after forming a single crystal semiconductor layer by, for example, the MOCVD method or the MBE method. That is,
First, the natural oxide film on the substrate 1 is removed at a high temperature of 800 ° C to 1000 ° C. Next, after growing amorphous gallium arsenide serving as a nucleus at a low temperature of 450 ° C. or lower to a thickness of about 0.1 to 2 μm by MOCVD or MBE, 500
The temperature is raised from ℃ to 700 ℃, the amorphous gallium arsenide is recrystallized to grow a gallium arsenide single crystal (two-step growth method). Next, post annealing such as annealing at a high temperature of 750 ° C. to 1000 ° C. and rapid cooling to a low temperature of 600 ° C. or less is repeated several times (temperature cycle method) is performed. In this case, trimethylgallium [(CH ₃ ) ₃ Ga] or the like is used as a raw material of gallium, arsine [AlH ₃ ] or the like is used as a raw material of arsenic, and trimethylaluminum [(CH ₃ ) is used as a raw material of aluminum.
₃ Al] or the like is used.

The layer 2a containing impurities of opposite conductivity type
Is, for example Zn, 10 a semiconductor impurity element such as Cd ¹⁶
The layer 2b containing about 10 to 10 ¹⁹ cm ^{−3 and} containing one conductivity type impurity contains about 10 ¹⁶ to 10 ¹⁹ cm ^{−3 of} an impurity element such as S, Se, Te, Ge, and Si.

The layer 2 containing impurities of the opposite conductivity type
The layer 2b containing a or one conductivity type impurity may be formed by a plurality of layers having different mixed crystal ratios of compounds. The layer 2a containing the impurity of the opposite conductivity type is formed in a smaller area than the layer 2b containing the impurity of one conductivity type. That is, the layer 2b containing the impurity of one conductivity type is also formed so that the surface thereof is partially exposed.

A protective film 5 made of, for example, a silicon nitride film is formed on the surface of the island-shaped semiconductor layer 2.
The common electrodes 4a, 4b made of, for example, gold (Au) or the like so as to extend from the exposed portion of the layer 2b containing one conductivity type impurity of the island-shaped semiconductor layer 2 to the vicinity of the end face of the substrate 1.
Are formed. Every other island-shaped semiconductor layer 2 is alternately connected to the common electrodes 4a and 4b. That is, the island-shaped semiconductor layer 2 is divided into two groups, and the common electrodes 4a and 4b are provided for each group.

Further, the individual electrode 3 is formed so as to extend from the surface of the layer 2a containing the impurity of the opposite conductivity type in the island-shaped semiconductor layer 2 through the wall surface on the opposite side to the vicinity of the end face on the opposite side. Has been done. One individual electrode 3 is formed for each adjacent island-shaped semiconductor layer 2. That is, one individual electrode 3 is provided for each semiconductor light emitting element belonging to a different group. The wide portion of the individual electrode 3 serves as an electrode pad for wire bonding for connecting to an external circuit. By selecting a combination of the individual electrodes 3 and the common electrodes 4a and 4b, it is possible to select individual semiconductor light emitting elements to emit light.

FIG. 3 is a circuit diagram showing an embodiment of the semiconductor light emitting device according to the present invention. In FIG. 3, 11 is a semiconductor light emitting element, 12 is a switching transistor, 13
Is a gate circuit, 14 is a latch circuit, and 15 is a shift register. In this semiconductor light emitting device drive circuit,
A non-emission data signal is input from DATA1 and DATA2 to the shift register 15 at the timing of the CLOCK signal and pulled up to the latch circuit 14 at the timing of the LATCH signal. This emission / non-emission data signal and STPB1
Alternatively, the logical product of STPB2 is used to determine whether the switching transistor 12 is turned on or not. When the switching transistor 12 is turned on, G1 is supplied from VDD1 via the semiconductor light emitting element 11.
A current is selectively supplied to ND1 or GND2 (common electrode 4a or 4b).

In the above embodiment, a plurality of semiconductor light emitting devices 2 are used.
Are connected to two common electrodes 4a and 4b by dividing them into two groups, and two semiconductor light emitting elements 2 belonging to each group are connected to each other.
The connection to the individual electrodes 3 has been described, but the plurality of semiconductor light emitting elements 2 are divided into three groups or more,
The semiconductor light emitting elements 2 may be connected to the individual electrode 3 in groups of three or more.

[0025]

As described above, according to the semiconductor light emitting device of the first aspect, the common electrode is provided for each group in which the island-shaped semiconductor layer serving as the light emitting element is divided into a plurality of groups, and the individual electrodes are provided. Since it is provided for each of the plurality of island-shaped semiconductor layers belonging to different groups, the formation density of the electrode pads is reduced, the workability of wire bonding is improved, and the wire bonding can be performed in a short time.

According to another aspect of the semiconductor light emitting device of the present invention, the opposite conductivity type semiconductor layer is provided on the one conductivity type semiconductor layer in a smaller area than the one conductivity type semiconductor layer, and the one conductivity type semiconductor layer is formed on the one conductivity type semiconductor layer. Since a common electrode connected to a group of one-conductivity-type semiconductor layers is provided from the substrate to the substrate and individual electrodes are provided from the opposite-conductivity-type semiconductor layer to the substrate, the island-shaped semiconductor layers are divided into a plurality of groups. It becomes possible to connect to the common electrode and to provide the individual electrodes for each of the plurality of island-shaped semiconductor layers belonging to different groups.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a semiconductor light emitting device according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is an electric circuit diagram showing an embodiment of a semiconductor light emitting device according to the present invention.

FIG. 4 is an electric circuit diagram showing an example of a conventional semiconductor light emitting device.

5 is a cross-sectional view taken along the line AA in FIG.

FIG. 6 is an electric circuit diagram showing a conventional semiconductor light emitting device.

[Explanation of symbols]

1 ... Substrate, 2 ... Island semiconductor layer, 3 ... Individual electrode, 4 ... Common electrode

Claims (2)

[Claims] 1. An island-shaped semiconductor layer comprising a semiconductor layer of one conductivity type and a semiconductor layer of opposite conductivity type is provided on a substrate, a common electrode is connected to the semiconductor layer of one conductivity type, and the semiconductor layer of opposite conductivity type is provided. In a semiconductor light emitting device provided by connecting individual electrodes, the common electrode is provided for each group in which the island-shaped semiconductor layers are divided into a plurality of groups, and the individual electrodes are provided for each of the plurality of island-shaped semiconductor layers belonging to different groups. A semiconductor light emitting device characterized by being provided. 2. An island-shaped semiconductor layer comprising a semiconductor layer of one conductivity type and a semiconductor layer of opposite conductivity type is provided on a substrate, a common electrode is connected to the semiconductor layer of one conductivity type, and the semiconductor layer of opposite conductivity type is provided. In a semiconductor light emitting device provided by connecting individual electrodes, the opposite conductivity type semiconductor layer is provided on the one conductivity type semiconductor layer in a smaller area than the one conductivity type semiconductor layer, and from this one conductivity type semiconductor layer. A semiconductor light-emitting device comprising: a common electrode connected to a group of one-conductivity-type semiconductor layers on the substrate; and individual electrodes on the opposite-conductivity-type semiconductor layer to the substrate.