JPH06244276A - Semiconductor light emitting device array - Google Patents

Abstract

PURPOSE:To provide an LED array of a certain structure wherein devices can be electrically isolated from each other even if a diffused region does not reach a PN junction by a method wherein a shallow diffusion region is formed in a short time causing less damage to a wafer when impurities are diffused for the isolation of devices. CONSTITUTION:A P-type semiconductor crystal layer 3 and an N-type semiconductor crystal layer 4 are successively laminated on a P-type semiconductor substrate 2, Zn is diffused into the semiconductor crystal layer 4 through its surface nearly half as deep as the depth of the layer 4 for the formation of P-type diffusion regions 5, a back electrode 6 is formed on all the underside of the substrate 2, light emitting device electrodes 7 are formed on the upside of the N-type semiconductor crystal layer 4, and diffusion region electrodes 8 provided separate from the light emitting device electrodes 7 are built on the P-type diffusion regions 5 respectively. A reverse voltage is applied to the diffusion region electrodes 8 to expand a depletion layer in width which is located at a boundary surface between the P-type diffusion region 5 and the N-type semiconductor crystal layer 4, whereby light emitting devices 10 can be electrically isolated from each other.

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 having a plurality of light emitting devices electrically separated from each other on a semiconductor substrate, and more particularly to the structure of the device separating portion.

[0002]

2. Description of the Related Art In recent years, a technique for integrating a LED array (semiconductor light emitting element array) at a high density for use as a light source for an optical printer or an information element using light has been proposed or developed. These LED arrays are used by linearly integrating light emitting diodes to form an array, but higher integration is required due to miniaturization of printers and higher image quality. As one of the methods for separating the light emitting elements on the substrate with high density, there is a method for diffusing impurities between the light emitting elements to electrically separate the light emitting elements. In such an LED array, a p-type GaAlAs layer and an n-type GaAlAs layer are sequentially laminated on a substrate by a liquid phase growth method to form a semiconductor wafer,
An insulating film such as SiO ₂ is deposited on the surface of this wafer, and n
P-type GaAlAs layer is photoetched so as to leave an insulating film corresponding to the light emitting region of the p-type GaAlAs layer, and zinc is diffused from the wafer surface by using this insulating film as a mask.
Forming a p-type isolation region reaching the AlAs layer to form an n-type GaA
By separating the 1As layer, the light emitting element is finely separated on the substrate.

[0003]

By the way, according to the above-mentioned LED array, P for separating the light emitting elements is used.
In order to form the p-type isolation region reaching the N-junction, the diffusion temperature must be increased and the diffusion time must be lengthened. For this reason, there is a possibility that the wafer, which is vulnerable to high heat, is damaged much and the quality of the LED array is degraded. Further, since the light is diffused deeply, the concentration distribution varies at the end of the diffusion region, so that the light emission output varies for each light emitting element of the LED array.
Further, since the diffusion time for forming the diffusion region for element isolation is long, there is a problem that the manufacturing cost becomes high. Further, since diffusion in the semiconductor crystal also progresses in the lateral direction, it becomes difficult to form a fine pattern of the light emitting element, and it becomes impossible to form the light emitting element at a high density.

Therefore, the present invention has been made by paying attention to the above points, and when diffusing impurities for element isolation, a shallow diffusion region is formed in a short time to reduce damage to the wafer. It is an object of the present invention to provide an LED array having a structure in which elements can be electrically isolated from each other even if the diffusion region does not reach the PN junction.

[0005]

As a means for achieving the above object, the present invention provides a semiconductor light emitting device array having a plurality of light emitting devices electrically separated on a substrate, and a PN junction from the surface. A plurality of diffusion regions formed by diffusing at a depth that does not reach, and a diffusion region electrode provided on the diffusion region and provided separately from the electrode for driving the light emitting element, and a boundary of the diffusion region. It is intended to provide a semiconductor light emitting device array characterized by expanding the depletion layer width and separating the light emitting devices by applying a voltage for controlling the depletion layer width generated on the surface to the diffusion region electrode. .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a side view showing the structure of the LED array of the present invention. FIG. 2 is a top view of the LED array of the present invention. As shown in FIG. 1, the LED array 1 has a P-
A P-AlGaAs semiconductor crystal layer 3 is formed on the GaAs substrate 2.
A semiconductor light emitting device having a PN junction formed by sequentially stacking (thickness 4 μm) and N-AlGaAs semiconductor crystal layer 4 (thickness 1 μm), wherein an N-type semiconductor from the surface of the N-type semiconductor crystal layer 4 is formed. Zn up to about half the depth of the crystal layer 4
Has a plurality of P-type diffusion regions 5 formed by diffusing.

Further, the back surface electrode 6 in ohmic contact with the entire bottom surface of the substrate 2, the light emitting element electrode 7 in ohmic contact with the upper surface of the N-type semiconductor crystal layer 4, and the light emitting element electrode in the upper surface of the P type diffusion region 5. Diffusion region electrode 8 provided separately from 7
But each is installed. Here, the light emitting element electrode 7
As shown in FIG. 2, the diffusion area electrode 8 is formed by opening the light output window 9 and the diffusion area electrode 8 is installed as a common electrode in all P-type diffusion areas 5. The light emitting element electrode 7 is installed therein. The semiconductor crystal sandwiched between the P-type diffusion regions 5 is one light emitting element 10. In this light emitting element 10, when a forward voltage is applied between the back electrode 6 and the light emitting element electrode 7, the P type diffusion region 5 is formed. The PN junction located between the P type diffusion region 5 and the P type diffusion region 5 becomes a light emitting region, and the light generated in this light emitting region is output from the light output window 9 on the upper surface of the N type semiconductor crystal layer 4.

As described above, in the LED array 1, since the diffusion depth of the P-type diffusion region 5 is about half that of the N-type semiconductor 4, the diffusion time can be shortened as compared with the conventional LED array. At the same time, the damage given to the LED array can be reduced. Further, it is possible to reduce the manufacturing cost by shortening the diffusion time. Further, since the light emitting element 10 can be patterned with higher density than the conventional one, it is possible to form a highly integrated LED array.

Next, the principle of electrically separating the light emitting elements 10 in the LED array 1 will be described. P
In the vicinity of the boundary between the N-junction P-type semiconductor and the N-type semiconductor,
A depletion layer is generated in the thermal equilibrium state. If a forward voltage is applied to the semiconductor of the PN junction, the movement of carriers causes a current to flow in the semiconductor crystal. However, when a reverse voltage is applied, carriers are attracted toward the electrode, and the width of the depletion layer generated in the thermal equilibrium state can be widened. The present invention utilizes the fact that the depletion layer width widens when a reverse voltage is applied to the semiconductor crystal of the PN junction, and electrically separates the light emitting elements arrayed on the substrate.

In the LED array 1 described above, a negative voltage is applied to the diffusion region electrode 8 to control the width of the depletion layer between the P-type diffusion region 5 and the N-type semiconductor crystal 4 by controlling the voltage applied to the diffusion region electrode 8. The light emitting element 10 is electrically separated completely by narrowing the current flowing in the semiconductor crystal when the light emitting element 10 is driven by expanding the light emitting element 10 until it reaches the vicinity of the PN junction.

Since the light emitting element electrode 7 for driving the light emitting element and the diffusion area electrode 8 for driving the element isolation area are separately formed, the element isolation of the light emitting element 10 depends on the drive current of the light emitting element 10. do not do. That is, even when the light emitting elements 10 need to be individually driven, the light emitting elements 10 can be reliably separated, and variations in light emission of the light emitting elements 10 are reduced.

The present invention is not limited to the structures shown in the above-mentioned embodiments. For example, the structure of the PN junction may be not only homojunction but also heterojunction or double heterojunction. Also, in the material of the semiconductor crystal, not only AlGaAs but also GaP, InP, InGaA
It is also applicable to an LED array composed of 1P, InGaAsP, or the like.

[0013]

As described above, according to the semiconductor light emitting element array of the present invention, the light emitting elements can be electrically separated without the diffusion depth reaching the PN junction portion. The diffusion time for forming the region is shorter than that in the conventional case, and the deterioration of the quality of the semiconductor light emitting device can be reduced. Further, since the diffusion region of the light emitting element separating portion may be shallower than that of the conventional light emitting element, it is possible to form the light emitting elements at a higher density than that of the conventional semiconductor light emitting element array. Further, since the diffusion area electrode for separating the light emitting elements and the electrode for driving the light emitting elements are provided separately, it is possible to ensure the separation of the light emitting elements even when the light emitting elements need to be driven individually. There is an effect that can be done to.

[Brief description of drawings]

FIG. 1 is a side view showing a structure of a semiconductor light emitting device of the present invention.

FIG. 2 is a top view of a semiconductor light emitting device of the present invention.

[Explanation of symbols]

 1 LED array (semiconductor light emitting element array) 2 P-GaAs substrate 3 P-AlGaAs semiconductor crystal layer 4 N-AlGaAs semiconductor crystal layer 5 P type diffusion region (diffusion region) 6 Back electrode 7 Light emitting element electrode (light emitting element driving electrode) ) 8 diffusion region electrode 10 light emitting element

Claims (1)

[Claims] 1. A semiconductor light emitting device array having a plurality of light emitting devices electrically isolated on a substrate, and a plurality of diffusion regions formed by diffusing from a surface to a depth not reaching a PN junction, A diffusion region electrode provided on the diffusion region and provided separately from the light emitting element driving electrode, and applying a voltage to the diffusion region electrode for controlling a depletion layer width generated at a boundary surface of the diffusion region. Accordingly, the semiconductor light emitting device array is characterized in that the depletion layer is widened to separate the light emitting devices.