JPH07193276A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To provide a semiconductor light emitting device wherein many light emitting elements can be driven by dividing them into a plurality of light emitting element groups, in order to reduce the number of connection terminals with external circuits, and imperfect connection with the external circuit is not caused. CONSTITUTION:In a semiconductor light emitting device wherein many island type light emitting elements 2 having semiconductor junction parts are formed on a semiconductor substrate 1 containing one conductivity type impurities, a plurality of regions 1a containing opposite conductivity type impurities are formed at part positions of the semiconductor substrate 1 for forming the light emitting elements 2, for a plurality of the light emitting elements 2.

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 a light source for exposing a photosensitive drum such as an LDE printer.

[0002]

2. Description of the Related Art A conventional semiconductor light emitting device is shown in FIGS.
As shown in FIG. 1, a semiconductor substrate 1 containing an impurity of one conductivity type
A large number of island-shaped light emitting elements 14 each of which is composed of a layer 12 containing one conductivity type impurity and a layer 13 containing opposite conductivity type impurities are formed on the upper surface of the semiconductor substrate 11. The front surface electrode 15 and the back surface electrode 16 are formed on the back surface, respectively. The surface electrode 15 is formed on the insulating film 17 at a position other than the contact portion with the layer 13 containing the opposite conductivity type impurity. Further, in the island-shaped light emitting element 14, a semiconductor junction is formed by the layer 12 containing an impurity of one conductivity type and the layer 13 containing an impurity of the opposite conductivity type.
Further, the semiconductor substrate 11 is formed of gallium arsenide (GaAs) or silicon (Si), and the light emitting element 14 is gallium arsenide or aluminum-gallium arsenide (AlGaAs).
And so on.

In this semiconductor light emitting device, the light emitting element 14 is selected to emit light by passing a current from the front surface electrode 15 of the light emitting element 14 desired to emit light to the back surface electrode 16.

[0004]

However, in this conventional semiconductor light emitting device, the surface electrodes 15 are provided on the large number of light emitting elements 14, respectively, but the large number of light emitting elements 14 are divided into groups and driven in a time division manner. There was a problem that I could not do it. If time-division driving is not possible, connection terminals 18 with external circuits corresponding to the number of light emitting elements 14 are required,
There is a problem that the connection with the external circuit becomes very complicated and causes a connection failure in the connection process.

The present invention has been made in view of the above problems of the prior art, and has a structure in which a large number of light-emitting elements 14 can be divided into a plurality of groups and driven in a time-division manner, and thus has a connection terminal to an external circuit. It is an object of the present invention to provide a semiconductor light emitting device in which the number of semiconductor light emitting devices is reduced so as not to induce connection failure in a connection process.

[0006]

In order to achieve the above object, the present invention provides a semiconductor light emitting device in which a large number of island-shaped light emitting elements having semiconductor junctions are formed on a semiconductor substrate containing one conductivity type impurity. A plurality of regions containing impurities of opposite conductivity type are formed for each of a plurality of light emitting elements in a portion of the semiconductor substrate where a light emitting element is formed.

[0007]

With the above-described structure, a large number of light emitting elements can be driven by being divided into groups for each of a plurality of light emitting elements, so that the number of connection terminals with an external circuit is reduced, resulting in poor connection with the external circuit. It is possible to provide a semiconductor light emitting device that does not induce the above.

[0008]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 1 is a view of a semiconductor light emitting device according to the present invention seen from the surface, FIG. 2 is a sectional view of the same, 1 is a semiconductor substrate containing impurities of one conductivity type, 2 is a light emitting element, 3 is a surface electrode, 4 Is a back electrode. The semiconductor substrate 1 is made of silicon (Si), gallium arsenide (GaAs), or the like, and contains one conductivity type impurity exhibiting p-type or n-type. In the vicinity of the surface of the semiconductor substrate 1, a plurality of regions 1a containing n-type or p-type impurities of opposite conductivity type are formed. The region 1a containing the opposite conductivity type impurity is formed by a thermal diffusion method or an ion implantation method in which a predetermined portion is covered with a silicon oxide (SiO ₂ ) film or the like. When the semiconductor substrate 1 is made of silicon, phosphorus (P), arsenic (As), antimony (S) are used as n-type impurities.
b), bismuth (Bi), and the like, and p-type impurities include boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Ti), and the like. When the semiconductor substrate 1 is made of gallium arsenide, the n-type impurities include zinc (Zn) and the p-type impurities include sulfur (S), selenium (Se), tellurium (Te), and the like. There is.

A plurality of light emitting devices 2 are formed on the region 1a of the semiconductor substrate 1 containing impurities of opposite conductivity type.
The light emitting element 2 is composed of a layer 2a containing an impurity of opposite conductivity type and a layer 2b containing an impurity of one conductivity type. For example, 6 regions are provided for each region 1a containing an impurity of opposite conductivity type of the semiconductor substrate 1.
Four pieces are formed. The layers 2a and 2b containing impurities of opposite conductivity type or impurities of one conductivity type are formed by metal organic chemical vapor deposition (MOCVD method) or the like, and for example, gallium arsenide (GaAs) or aluminum gallium arsenide (AlG).
aAs) or the like. When the layers 2a and 2b containing impurities of opposite conductivity type or impurities of one conductivity type are made n-type, zinc (Zn) or the like is used, and when they are made p-type, sulfur (S), selenium (Se), tellurium (Te). ) And so on.

On the semiconductor substrate 1 and the light emitting device 2,
Silicon nitride (SiN _x ) film and silicon oxide (Si
An insulating film 6 made of an O ₂ ) film or the like is formed. The insulating film 6 is formed by, for example, a plasma CVD method or the like.

A group selection electrode 7 is formed on a region 1a of the semiconductor substrate 1 containing impurities of opposite conductivity type, a front surface electrode 3 is formed on the light emitting element 2, and a back surface electrode is formed on the back surface side of the semiconductor substrate 1. 4 is formed. The front surface electrode 3, the back surface electrode 4, and the group selection electrode 7 are formed of aluminum (Al), gold (Au), chromium (Cr), or the like.

The surface electrode 3 is composed of an electrode 3a provided for each light emitting element 2 and an electrode 3b for connecting the electrodes 3a located in the same order for each group. That is, the surface electrode 3
The number of the terminals 8 for connecting to the external circuit is the same as the number of the light emitting elements 2 in one group.

FIG. 3 is a diagram for explaining how a voltage is applied to the semiconductor substrate 1 and the light emitting element 2. Figure 3 (a)
In the above example, the semiconductor substrate 1 is p-type, the region 1a containing an impurity of opposite conductivity type is n-type, and on the n-type region 1a,
The light emitting element 2 including the n-type semiconductor layer 2a and the p-type semiconductor layer 2b is formed. The insulating film 6 in FIG. 2 is omitted. In this semiconductor light emitting device, two first DC power supplies 8 and two second DC power supplies 9 are provided as DC power supplies. In this state, when a forward bias voltage is applied to the light emitting element 2 from the first DC power supply 8 and a reverse bias voltage is applied to the semiconductor substrate 1 from the second DC power supply 9, the current in the intermediate line 10 is reversed. Therefore, no current flows through the light emitting element 2. Further, as shown in FIG. 3B, when the forward bias voltage is applied to the light emitting element 2 from the first DC power source 8 and the forward bias voltage is applied to the semiconductor substrate 1 from the second DC power source 9, the intermediate line At 10, the current flows in the same direction, and the current flows through the light emitting element 2. Therefore, by changing the application direction of the bias voltage to the group selection electrode 7 and the back surface electrode 9,
The supply of current to the light emitting element 2 can be controlled on a group-by-group basis, and time-divisional driving becomes possible.

[0014]

As described above, according to the semiconductor light emitting device of the present invention, a plurality of regions containing impurities of opposite conductivity type are formed in a portion of a semiconductor substrate containing impurities of one conductivity type where a semiconductor light emitting element is formed. Since a plurality of semiconductor light emitting elements are formed for each semiconductor light emitting element, it is possible to drive a large number of light emitting elements divided into groups for each of the plurality of light emitting elements, thus reducing the number of connection points with external circuits and connecting with external circuits. It is possible to provide a semiconductor light emitting device that does not induce defects.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an embodiment of a semiconductor light emitting device according to the present invention.

FIG. 3 is a diagram showing a voltage applied state to a semiconductor light emitting device according to the present invention, (a) shows a state in which a reverse bias voltage is applied to a semiconductor substrate, and (b) shows a forward bias voltage applied to the semiconductor substrate. Shows a state in which is applied.

FIG. 4 is a plan view showing a conventional semiconductor light emitting device.

FIG. 5 is a cross-sectional view showing a conventional semiconductor light emitting device.

[Explanation of sign]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 1a ... Area containing impurities of opposite conductivity type, 2 ... Light emitting element, 3 ... Surface electrode, 4 ...
..Back surface electrodes

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B41J 2/455

Claims (1)

[Claims] 1. A semiconductor light emitting device having a large number of island-shaped semiconductor light emitting elements having semiconductor junctions formed on a semiconductor substrate containing one conductivity type impurity. A semiconductor light emitting device, wherein a plurality of regions containing conductive impurities are formed for each of a plurality of semiconductor light emitting elements.