JPH07131070A - Semiconductor light emitting element and semiconductor light emitting element array - Google Patents

Abstract

PURPOSE:To reduce element resistance and at the same time achieve a high light output by forming an electrode film consisting of a metal transparent conductive film with ohmic junction properties on a light output surface and a transparent conductive film with the maximum transmittance near the peak wavelength of output light and then connecting a metal wiring to the electrode film. CONSTITUTION:A light emitting diode array 1 covers a light output surface 12 and forms a metal transparent conductive film 13a indicating ohmic junction properties and an oxide semiconductor transparent conductive film 13 which protects it and has the maximum transmittance near the peak wavelength of output light. An electrode 14 for wiring is formed in contact with the peripheral part which is other than that directly above the light output surface 12 of the electrode film 13, thus preventing ohmic junction property from being lost and output light from being sheldeel by the light output surface 12. Further. the reflection of light emitted externally from the light output surface 12 on the interface is prevented. light transmission property is improved, and a low element resistance and a high light output are achieved. Also, a light emitting element 9 can be integrated with a high density.

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, and more particularly to a surface emitting type semiconductor light emitting device and a semiconductor light emitting device array.

[0002]

2. Description of the Related Art Conventionally, a semiconductor light emitting element integrated in high density to form an array has been used as a light source for an optical printer or an information processing element using light. 2. Description of the Related Art In recent years, with the miniaturization of printers and higher image quality, higher brightness and higher density of light emitting elements are required. In a light emitting diode monolithic array in which semiconductor crystal layers laminated on a substrate are electrically separated to form light emitting elements in rows, a mesa-type etching method is often used as a method for separating the light emitting elements. There is.

Next, an example of a conventional light emitting diode array by the mesa type etching method will be described with reference to FIGS. 3 is a partially enlarged plan view in the column direction showing the structure of an example of a conventional light emitting diode array, and FIG.
FIG. 6 is a sectional view taken along line BB of In both figures, a conventional light emitting diode array 21 has an n-type GaAs substrate 2 with n
-GaAs buffer layer 3, n-Al _0.45 Ga _0.55 As and n-AlAs as one set, 25 sets of reflective layers 4, n-Al _0.7 Ga _0.3 As clad layer 5, p-Al
_0.3 Ga _0.7 As light emitting layer 6, p-Al _0.7 Ga _0.3 As
The semiconductor crystal layer in which the clad layer 7 is sequentially laminated has a plurality of light emitting elements 29 separated by the separation groove 10 by etching, and the semiconductor crystal layer upper surface excluding the electrode bonding portion and the surface of the separation groove 10 have SiN. An antireflection film 30 is formed. An electrode 15 is provided on the entire lower surface of the substrate 2. Further, an electrode 23 is provided on the light output surface 22 on the upper surface of each light emitting element 29 via a contact layer 28, and an electrode 24 for wiring is laid so as to crawl on a mesa type etching groove.
Has been pulled out.

Here, each film of the reflection layer 4 is
It is a material selected to maximize the reflectance by interference, and the light emitted from the light emitting layer 6 to the substrate 2 side is reflected by the reflective layer 4 to eliminate the light absorption by the substrate 2.
Usually, this film thickness d is given by the following equation when the refractive index of the member is n and the emission center wavelength is λp. d = λp / 4n By increasing the number of sets, the performance (maximum reflectance) of the reflective layer 4 is improved.

Further, the SiN antireflection film 30 removes the reflection component of the output light on the light output surface 22 by interference and maximizes the transmittance, and at the same time, between the electrode 24 and the semiconductor crystal layer. It also acts as an insulator by interposing it.

[0006]

By the way, according to the conventional light emitting diode array 21 having the above-mentioned structure, when the electrode 23 on the light output surface 22 is enlarged, the heat generated from the element due to the decrease in resistance is generated. Although the quantum efficiency is suppressed and the quantum efficiency is improved, the area where the output light is blocked by the electrode 23 is increased and the output is decreased. Conversely, when the electrode 23 is decreased, the resistance is increased and the light emission efficiency is decreased. There is a problem that a sufficient light emission output cannot be obtained because the current spread cannot be sufficiently taken due to the thinning due to the reduction in thickness. Further, when the light emitting elements are integrated with higher density, the light output surface 22 is inevitably small and the light output surface 22 is
There is a problem that the light output is further weakened along with the blocking of the output light by the upper electrode 23.

Therefore, the present invention has been made by paying attention to the above points, and a semiconductor light emitting element which realizes a low element resistance and a high light output, and a semiconductor light emitting element in which the semiconductor light emitting elements are integrated at a high density are provided. An object is to provide an element array.

[0008]

A semiconductor light emitting device according to the present invention has a structure in which a semiconductor crystal layer including a light emitting layer is laminated on a substrate,
In a surface emitting semiconductor light emitting device that outputs light from the light emitting layer from a light output surface on the upper surface of the semiconductor crystal layer, a metal transparent conductive film exhibiting ohmic junction characteristics and a maximum wavelength near the peak wavelength of the output light. The above object is achieved by forming an electrode film made of a transparent conductive film having a transmittance on the light output surface and connecting a metal wiring to the electrode film.

The electrode film is formed so as to cover the entire surface of the light output surface and its peripheral portion, and the metal wiring is formed in contact with a portion of the electrode film that does not shield the light output surface. It achieves the purpose.

Further, the semiconductor light emitting device array of the present invention achieves the above-mentioned object by forming a plurality of the semiconductor light emitting devices in a row.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same components as those of the above-described conventional example or components corresponding to those of the conventional example are denoted by the same reference numerals, and the description thereof may be omitted. 1 is a partially enlarged plan view showing a structure of a light emitting diode array which is an embodiment of a semiconductor light emitting device and a semiconductor light emitting device array of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. .

In both figures, the light emitting diode array 1 of this embodiment has an electrode film 13 formed to cover the entire light output surface 12 and its peripheral portion, as compared with the light emitting diode array 21 of the conventional example. The main difference is that an electrode 14 for wiring is connected to a peripheral portion of the electrode film 13 that does not shield the light output surface 12. The light emitting diode array 1 of this embodiment will be described together with its manufacturing process. The semiconductor light emitting element array 1 is first of
Se is added on the GaAs substrate 2 so that the carrier concentration is 2 ×.
An n-GaAs buffer layer 3 having a thickness of 10 ¹⁸ cm ^-3 and a thickness of 0.5 μm is laminated, and then Se is added to make the carrier concentration 2 ×.
N-Al _0.45 Ga with a thickness of 10 ¹⁸ cm ^-3 and a thickness of 0.05 μm
Twenty-five sets of the reflection films 4 are laminated, with _0.55 As and n-AlAs having a thickness of 0.057 μm as one set.

Further, Se is added on the reflective film 4 to make n-Al _0.7 having a carrier concentration of 1 × 10 ¹⁸ cm ^-3 and a film thickness of 5 μm.
Ga _0.3 As clad layer 5 and Zn-added p-Al _0.3 with a carrier concentration of 5 × 10 ¹⁷ cm ^-3 and a film thickness of 0.5 μm.
Ga _0.7 As light emitting layer 6 and Zn-added p-Al _0.7 Ga _0.3 with a carrier concentration of 8 × 10 ¹⁷ cm ^-3 and a film thickness of 2 μm.
As clad layer 7 and Zn are added so that the carrier concentration is 1 ×
A p-GaAs contact layer 8 having a thickness of 10 ¹⁹ cm ^-3 and a thickness of 0.01 μm is laminated. All of these are performed using a metal organic chemical vapor deposition method (MOCVD method), a molecular beam epitaxy method (MBE method), or the like.

Next, a separation groove 10 for separating the plurality of light emitting elements 9 is formed. The SiO ₂ film was laminated on the semiconductor layer by vapor deposition (CVD), and etching the SiO ₂ film into a desired pattern using conventional lithographic techniques after. Using the remaining SiO ₂ film as an etching mask, the separation groove 10 is formed using a hydrochloric acid etching solution. Further, after laminating a SiO ₂ film 11 as a protective film on the entire surface by vapor deposition, by conventional lithography and etching removing the SiO ₂ film 11 of the light output surface 12 of each light emitting element 9.

Next, an electrode film 13 is formed on the light output surface 12. Here, the electrode film is formed from a transparent conductive film, and this transparent conductive film is a film that has both large conductivity and high translucency in the visible region, and is roughly classified into a metal transparent conductive film and an oxide semiconductor. There is a transparent conductive film. Therefore, a metal transparent conductive film having ohmic contact characteristics with the semiconductor is laminated on the light output surface of the semiconductor light emitting device. This metal transparent conductive film is 0.01μ
Since it needs to be made very thin as m or less and the film strength is poor, an oxide semiconductor transparent conductive film is laminated on the upper surface as a protective film. Further, if the refractive index and the film thickness of this transparent conductive film are set appropriately, reflection can be reduced and the transmittance can be improved. The film thickness d is such that the refractive index of the member is n and the emission center wavelength is λ.
When p and m are positive integers, they are given by the following equation. d = (2m−1) λp / 4n

Here, after the Ag film 13a of the metal transparent conductive film is laminated by 0.005 μm and the Cd ₂ SnO ₄ film 13b of the oxide semiconductor transparent conductive film is laminated by 0.4 μm by, for example, a sputtering method, a usual lithography technique and etching are carried out. By the technique, the Ag film 13a and the Cd ₂ SnO ₄ film 13b are formed by removing all but the part covering the entire light output surface 12 and its peripheral portion. With these transparent conductive films, the electrode film 13 having the maximum transmittance is formed in the vicinity of the peak wavelength of the light output from the light emitting layer 6.

Then, the light output surface 1 of the electrode film 13 is formed by the sputtering method, the lithography technique and the etching technique.
2. A wiring electrode 14 made of Al and an electrode 15 on the lower surface of the substrate are formed in contact with the peripheral portion other than directly above. The wiring electrode 14 is formed so as to crawl the separation groove 9, and S
The iO ₂ film 11 is insulated from the semiconductor crystal layer.

According to the light emitting diode array 1 of the embodiment having the above-mentioned structure, the transparent metal conductive film (A) covering the light output surface 12 and exhibiting ohmic contact characteristics.
and the oxide semiconductor transparent conductive film (Cd ₂ SnO ₄ film 13b) which has the maximum transmittance in the vicinity of the peak wavelength of the output light by protecting it. Since the electrode 14 is formed in contact with the peripheral portion of the electrode film 13 other than immediately above the light output surface 12, the ohmic contact is not impaired, and the output light is not blocked by the light output surface 12. Further, it is possible to eliminate the reflection of the light emitted from the light output surface 12 to the outside at the interface, improve the translucency, and realize low element resistance and high light output. Therefore, it is possible to integrate the light emitting elements 9 in a very high density while obtaining a sufficient light output.

It should be noted that the specific numerical values, material names, manufacturing methods, etc. used in this embodiment are merely used for explanation, and the semiconductor light emitting device and the semiconductor light emitting device array according to the present invention are However, the present invention is not limited to these.

[0020]

As described above, according to the semiconductor light emitting device of the present invention, the metal transparent conductive film having the ohmic junction characteristic on the light output surface and the maximum transmission in the vicinity of the peak wavelength of the output light. Since an electrode film made of a transparent conductive film having a certain ratio is formed and a metal wiring is connected to this electrode film, it is possible to reduce the element resistance and realize a high light output.

Further, since the electrode film is formed so as to cover the entire surface of the light output surface and its peripheral portion and the metal wiring is formed in contact with the portion of the electrode film which does not shield the light output surface, the device resistance is lower and the device resistance is higher. The light output can be obtained.

Further, according to the semiconductor light emitting device array of the present invention, it is possible to realize a low device resistance and obtain a high light output, and to integrate the light emitting devices in a very high density.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view showing a structure of a light emitting diode array which is an embodiment of a semiconductor light emitting device and a semiconductor light emitting device array of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a partially enlarged plan view showing the structure of an example of a conventional light emitting diode array.

4 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

1 Light Emitting Diode Array 2 Substrate 3 Buffer Layer (Semiconductor Crystal Layer) 4 Reflective Layer (Semiconductor Crystal Layer) 5 Clad Layer (Semiconductor Crystal Layer) 6 Light Emitting Layer (Semiconductor Crystal Layer) 7 Clad Layer (Semiconductor Crystal Layer) 8 Contact Layer (Semiconductor crystal layer) 9 Light emitting element 10 Separation groove 11 SiO ₂ film 12 Light output surface 13 Electrode film 13a Ag film (metal transparent conductive film) 13b Cd ₂ SnO ₄ film (oxide transparent conductive film) 14 Electrode (metal wiring)

Claims (3)

[Claims] 1. A surface-emitting type semiconductor light emitting device in which a semiconductor crystal layer including a light emitting layer is laminated on a substrate, and light from the light emitting layer is output from a light output surface on the upper surface of the semiconductor crystal layer, wherein an ohmic contact is provided. An electrode film composed of a metal transparent conductive film exhibiting bonding characteristics and a transparent conductive film having a maximum transmittance in the vicinity of the peak wavelength of output light is formed on the light output surface, and metal wiring is formed on the electrode film. A semiconductor light emitting device characterized in that 2. The electrode film is formed so as to cover the entire surface of the light output surface and a peripheral portion thereof, and the metal wiring is formed in contact with a portion of the electrode film that does not shield the light output surface. The semiconductor light emitting device according to claim 1. 3. A semiconductor light emitting device array in which a plurality of semiconductor light emitting devices according to claim 1 or 2 are formed in a row.