JP2005310937A - Light emitting diode array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-power light emitting diode array which is improved in optical fetch efficiency by optimizing the thickness of an insulating film and a protective film. <P>SOLUTION: A luminescence wavelength exists between 700 nm or more and 750 nm or less, and the protective film is composed of a second insulating film 19 composed of oxidization silicon one by one from the uppermost surface, a protective film 14 composed of silicon nitride, and a first insulating film 11 composed of oxidization silicon. Further, the semiconductor layer directly under the second insulating layer is formed with compound semiconductors 4-6 expressed with a general formula Al<SB>x</SB>Ga<SB>1-x</SB>As (0.5≤x≤0.8). Moreover, the film thickness of the first insulating film 11 is 30 nm or less to 50 nm or less, and the film thickness of the protective film 14 composed of silicon nitride is set to d1, and when the film thickness of the second insulating film 19 is set to d2, reference symbols (d1, d2) are arbitrary values in a closed region in a specific range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting diode array, and more particularly to a light emitting diode array suitable for use in an electrophotographic printer light source.

  At present, a laser system and a light emitting diode array system are mainly used as a light source of an electrophotographic printer. In particular, the light emitting diode array method has a feature that the optical path length is shorter than that of the laser method, so that the printer can be miniaturized and printing of a large size becomes easy.

  More recently, printers have been downsized, and a light-emitting diode array with higher definition and higher output has been demanded.

  FIG. 8 is a top view of a conventional light emitting diode array, and FIG. 9 is a cross-sectional structural view of the B-B ′ portion.

  As shown in FIG. 8, the conventional light emitting diode array has a plurality of light emitting diode portions 10 arranged in a line on a chip.

  As shown in FIG. 9, the cross-sectional structure is such that a p-type GaAs conductive layer 2, a p-type aluminum gallium arsenide (AlGaAs) etching stopper layer 3, a p-type AlGaAs cladding layer on a semi-insulating gallium arsenide (GaAs) substrate 4, a p-type AlGaAs active layer 5, an n-type AlGaAs cladding layer 6, and an n-type GaAs cap layer 7 are sequentially stacked to form a double heterostructure.

  The element separation of the light emitting diode part 10 is mesa-etched from the n-type GaAs cap layer 7 to the semi-insulating GaAs substrate 1 to separate the elements.

  The cathode contact electrode 8 and the anode contact electrode 15 for energizing the light emitting diode are formed by depositing metal on the mesa top surface of the n-type GaAs cap layer 9 and the p-type GaAs conductive layer 2 and alloying them. It is formed by. These electrodes are extended to a cathode bonding pad 17 and an anode bonding pad 18 by gold (Au) wirings 16, respectively.

  The light generated in the active layer 5 of the light emitting diode unit 10 is absorbed by the n-type GaAs cap layer 7 and cannot be transmitted. Therefore, the n-type GaAs cap layer 7 is removed by etching, and a light emitting portion 12 (light emitting portion surface 12a) as a light extraction portion is provided. On the surface of the light emitting portion surface 12a, a silicon oxide (SiO, Phospho Silicate Glass) insulating film 11 and a SiO insulating film 19, which are protective films intended to insulate from the Au wiring 16, and a denser protective film. A silicon nitride (SiN) protective film 14 is provided.

  In addition, as a light emitting diode array provided with the light emission part which is the above light extraction parts, there exist some which were disclosed by Unexamined-Japanese-Patent No. 2003-8056 (refer patent document 1), for example.

Further, as a reference to the thickness of the protective film, for example, there is Japanese Patent No. 3450145 (see Patent Document 2), which describes that it is formed to about 3000 angstroms.
Japanese Patent Laying-Open No. 2003-8056 (FIG. 2, light emitting unit 11) Japanese Patent No. 3450145 (paragraph numbers 0016 and 0018)

  By the way, in the structure of the light emitting diode array of FIG. 9, the light from the light emitting portion surface 12a passes through the SiO insulating film 11, the SiO insulating film 19, and the SiN protective film 14 and is extracted to the outside. Since the film thicknesses of these insulating films and protective films are approximately the same as the wavelength of light, the light extraction efficiency may be significantly reduced due to reflection and interference at the interface of each layer.

  However, in the prior art, with respect to these insulating film and protective film, the film thickness has not been optimized in consideration of the properties as the wave of light.

  Accordingly, an object of the present invention is to provide a high-power light-emitting diode array in which the light extraction efficiency is improved by solving the above-described problems and optimizing the thicknesses of the insulating film and the protective film.

  In order to achieve the above object, the present invention is configured as follows.

The light-emitting diode array according to claim 1 has a plurality of compound semiconductor layers epitaxially grown on a substrate and having a plurality of light-emitting diode portions that are insulated and divided, and the light-emitting surface of the light-emitting diode portion is formed from an insulating film. In a light emitting diode array coated with a protective film,
The emission wavelength is in the range of 700 nm to 750 nm,
The protective film is formed of a second insulating film made of silicon oxide (SiO), a protective film made of silicon nitride (SiN), and a first insulating film made of silicon oxide (SiO) sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 30 nm or less,
Further, when the thickness of the protective film made of silicon nitride is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (647, 421), ( 650, 392), (660, 366), (670, 365), (680, 368), (690, 371), (700, 375), (710, 381), (720, 391), (730, 416), (730, 428), (710, 475), (700, 486), (690, 493), (680, 497), (670, 496), (660, 491), (647, 464) , (647, 421) is an arbitrary value in a closed region that sequentially connects the points with a straight line.

A light-emitting diode array according to a second aspect of the present invention has a plurality of compound semiconductor layers epitaxially grown on a substrate, and has a plurality of light-emitting diode portions that are insulated and divided, and the light-emitting surface of the light-emitting diode portion is formed from an insulating film. In a light emitting diode array coated with a protective film consisting of:
The emission wavelength is in the range of 700 nm to 750 nm,
The protective film is formed of a second insulating film made of silicon oxide (SiO), a protective film made of silicon nitride (SiN), and a first insulating film made of silicon oxide (SiO) sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 35 nm or less,
When the thickness of the protective film made of silicon nitride (SiN) is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 436). ), (650, 408), (660, 385), (670, 378), (680, 378), (690, 380), (700, 384), (710, 392), (719, 412), (719, 432), (710, 458), (700, 473), (690, 483), (680, 488), (670, 490), (660, 487), (650, 477), (646) , 462) and (646, 436) are arbitrary values within a closed region that sequentially connects the points with straight lines.

A light emitting diode array according to a third aspect of the present invention includes a plurality of compound semiconductor layers epitaxially grown on a substrate and having a plurality of light emitting diode portions that are insulated and divided, and a light emitting portion surface of the light emitting diode portion is formed from an insulating film. In a light emitting diode array coated with a protective film consisting of:
The emission wavelength is in the range of 700 nm to 750 nm,
The protective film is formed of a second insulating film made of silicon oxide (SiO), a protective film made of silicon nitride (SiN), and a first insulating film made of silicon oxide (SiO) sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 40 nm or less,
When the thickness of the protective film made of silicon nitride (SiN) is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 439). ), (650, 417), (660, 395), (670, 388), (680, 386), (690, 389), (700, 395), (709, 414), (709, 430), (700, 456), (690, 470), (680, 479), (670, 483), (660, 482), (650, 474), (646, 462), (646, 439) It is an arbitrary value in a closed region that sequentially connects with a straight line.

A light-emitting diode array according to a fourth aspect of the present invention has a plurality of compound semiconductor layers epitaxially grown on a substrate and has a plurality of light-emitting diode portions that are insulated and divided, and the light-emitting surface of the light-emitting diode portion is formed from an insulating film. In a light emitting diode array coated with a protective film consisting of:
The emission wavelength is in the range of 700 nm to 750 nm,
The protective film is formed of a second insulating film made of silicon oxide (SiO), a protective film made of silicon nitride (SiN), and a first insulating film made of silicon oxide (SiO) sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 45 nm or less,
When the thickness of the protective film made of silicon nitride (SiN) is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 447). ), (650, 424), (660, 404), (670, 397), (680, 395), (690, 399), (699, 416), (699, 429), (690, 454), (680, 467), (670, 474), (660, 475), (650, 469), (646, 455), (646, 447) any value within the closed region that sequentially connects the points. It is characterized by being.

A light-emitting diode array according to a fifth aspect of the present invention includes a plurality of compound semiconductor layers epitaxially grown on a substrate and having a plurality of light-emitting diode portions that are insulated and divided, and a light-emitting surface of the light-emitting diode portion is formed from an insulating film. In a light emitting diode array coated with a protective film,
The emission wavelength is in the range of 700 nm to 750 nm,
The protective film is formed of a second insulating film made of silicon oxide (SiO), a protective film made of silicon nitride (SiN), and a first insulating film made of silicon oxide (SiO) sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 50 nm or less,
When the thickness of the protective film made of silicon nitride (SiN) is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (648, 442). ), (650, 432), (660, 412), (670, 405), (680, 406), (688, 417), (688, 433), (680, 452), (670, 463), (660, 467), (650, 461), (648, 455), (648, 442) each point is an arbitrary value within a closed region that is connected by a straight line.

<Key points of the invention>
The behavior of light in a semiconductor thin film is described in “Optical Engineering Handbook” (Kose et al., Asakura Shoten (1986)).

  When attention is paid only to the property as the wave of light, there is a region where the light extraction efficiency increases in addition to the range described in the above claims. This is because the same effect can be obtained with respect to multi-order diffracted light.

  However, there is a concern that an increase in the film thickness more than necessary may have adverse effects such as a decrease in light extraction efficiency due to light absorption and a reduction in device life due to a decrease in heat dissipation capability. Furthermore, since the raw materials necessary for forming the thick film increase and the formation time is prolonged, the cost is directly increased.

  On the other hand, in order for the second insulating film made of silicon oxide (SiO) and the protective film made of silicon nitride (SiN) to sufficiently perform their original functions as an insulating film and a protective film, respectively, 300 nm and 500 nm or more, respectively. The thickness of is required.

  Considering the above conditions, it can be said that the range described in the claims is optimal.

With respect to the substrate constituting the light emitting diode array according to the present invention and the material constituting the compound semiconductor layer epitaxially grown thereon, the semiconductor layer immediately below the second insulating film has the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8) is not particularly limited except that it is limited to the compound semiconductor represented by ≦ x ≦ 0.8). However, in consideration of lattice matching with the semiconductor layer immediately below the second insulating film, it is composed of GaAs and AlGaAs-based materials. It is desirable.

  It is desirable that nothing is laminated directly on the first insulating film and is in direct contact with the atmosphere or an atmosphere equivalent thereto, but a material having a thickness sufficiently larger than the wavelength of light and transparent to the wavelength is used. By laminating, the first insulating film and the underlying film may be further protected.

  According to the present invention, in the light-emitting diode array in which the light-emitting portion surface of the light-emitting diode portion is covered with a protective film made of an insulating film, the light extraction efficiency is improved by optimizing the thickness of the insulating film and the protective film. A high power light emitting diode array can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a top view of a light-emitting diode array according to the present invention, and FIG. 2 shows a cross-sectional structure of an A-A ′ portion of the light-emitting diode array.

  This light-emitting diode array has a plurality of light-emitting diode portions 10 which are formed by epitaxial layers each having a plurality of crystal layers stacked on a semi-insulating GaAs substrate 1 and are insulated and divided. The surface 12a is covered with the SiO insulating film 11 (first insulating film) and the SiN protective film 14, and further covered with the SiO insulating film 19 (second insulating film).

  In this light-emitting diode array, only the film thicknesses of the SiO insulating film 11 (first insulating film), the SiN protective film 14, and the SiO insulating film 19 (second insulating film) are different from the conventional ones. It has the same structure.

  In detail, as shown in FIG. 1, the light emitting diode array is formed on a semi-insulating GaAs substrate 1 with a mesa-type light emitting diode portion 10 that emits light when voltage is applied. On the top surface, a large number of light emitting portions 12 for extracting light emitted from the light emitting diode portions 10 to the outside are provided in a row, each insulated by a mesa etching groove 13.

  Further, along the row of the light emitting portions 12, an anode contact electrode 15 for applying a voltage to the light emitting diode portion is formed on one mesa groove surface, and each other mesa top surface is provided with each electrode. A cathode contact electrode 8 is formed for each light emitting portion 12.

  Further, the cathode contact electrode 8 is electrically connected to a cathode bonding pad 17 for connection to an external element through an Au wiring 16.

  FIG. 2 shows a sectional view of the structure of the light emitting diode array.

  As shown in FIG. 2, the light-emitting diode section 10 of this light-emitting diode array has a p-type GaAs conductive layer 2, a p-type AlGaAs etching stopper layer 3, a p-type AlGaAs cladding layer 4, p on a semi-insulating GaAs substrate 1. A type AlGaAs active layer 5, an n-type AlGaAs cladding layer 6, and an n-type GaAs cap layer 7 are sequentially stacked, and are formed in a mesa shape by a mesa etching groove 13.

  Further, as described above, the cathode contact electrode 8 is formed on the top surface of the mesa of the light emitting diode section 10, and the anode contact electrode 15 is the p-type GaAs conductive layer 2 that is the mesa groove surface of the light emitting diode 10. Formed on top.

  Next, the manufacturing method of this light emitting diode array will be described together with the operation.

On the (100) surface of the semi-insulating GaAs substrate 1, a p-type GaAs conductive layer 2 having a carrier concentration of 4 × 10 ¹⁹ cm ⁻³ is 1 μm and a carrier concentration is 3 × 10 ¹⁹ cm by metal organic chemical vapor deposition (MOVPE). ^-3 p-type AlGaAs etching stopper layer 3 is 0.5 μm, p-type AlGaAs cladding layer 4 having a carrier concentration of 3 × 10 ¹⁸ cm ⁻³ is 1 μm, and p-type AlGaAs active layer 5 having a carrier concentration of 1 × 10 ¹⁸ cm ^−3. 1 μm, an n-type AlGaAs cladding layer 6 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ is grown to 3 μm, and an n-type GaAs cap layer 7 having a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ is successively grown to 0.5 μm.

  The n-type GaAs cap layer 7 which is the uppermost layer is removed by wet etching to leave only a part 9 of the n-type GaAs cap layer in order to form the cathode contact electrode 8.

  Then, a mesa etching groove 13 is formed by wet etching in order to electrically isolate each light emitting diode portion 10. The depth of the mesa etching groove 13 is 7.0 μm at which the semi-insulating GaAs substrate 1 is exposed.

  Further, a SiO insulating film (first insulating film) 11 is grown by a vapor deposition (CVD) method so as to cover the entire surface.

Then, the SiO insulating film 11 in the cathode contact electrode 8 portion is removed by hydrofluoric acid, and the SiO insulating film 11 in the portion forming the anode contact electrode 15 is removed by dry etching using a gas such as CHF ₃₃ / O ₂₂ . The cathode contact electrode 8 is formed by evaporating and alloying gold germanium (AuGe) / nickel (Ni) / Au on the n-type GaAs cap layer 9. The anode contact electrode 15 is formed by evaporating and alloying gold zinc (AuZn) / Ni / Au on the p-type GaAs conductive layer 2 exposed at the bottom of the mesa etching groove. These electrodes are drawn out to the portions of the cathode bonding pad 17 and the anode bonding pad 18 by the Au wiring 16.

  Next, in order to prevent intrusion of moisture and the like, the entire surface is covered with a SiN protective film 14 which is a denser film.

  Further, the entire surface is covered with a SiO insulating film 19 (second insulating film).

  Finally, the protective film on the bonding pads 17 and 18 is removed, and the light emitting diode array is manufactured in a state where electric wiring is possible. At this time, by changing the growth times of the SiO insulating film (first insulating film) 11, the SiN protective film 14, and the SiO insulating film (second insulating film) 19, the light emitting diode array having a combination of different film thicknesses. A to Z were obtained.

  A voltage of 3 V was applied to each of them, and the light emission output and the light emission peak wavelength were measured using an optical power meter and an optical spectrum analyzer.

表１において、発光ダイオードＡ〜Ｚは全て発光ピーク波長が７００nm以上７５０nm以下の範囲にある。このうち発光ダイオードＡ〜Ｏが本発明の実施例であり、発光出力が１０．１〜１０．８［ａ．ｕ．］と高くなっている。一方、発光ダイオードＰ〜Ｚは比較例であり、発光出力は６．２〜８．４［ａ．ｕ．］と低いものとなっている。なおＳｉＯ絶縁膜（第２絶縁膜）１９の直下の半導体層（ｐ型ＡｌＧａＡｓクラッド層４、ｐ型ＡｌＧａＡｓ活性層５、ｎ型ＡｌＧａＡｓクラッド層６）は、一般式Ａｌ_xＧａ_1-xＡｓ（０．５≦ｘ≦０．８）で表される化合物半導体となっている。 Table 1 shows the film thickness, light emission output, and light emission peak wavelength of the SiO insulating film 11, the SiN protective film 14, and the SiO insulating film 19 of the light emitting diodes A to Z.

In Table 1, all of the light emitting diodes A to Z have a light emission peak wavelength in the range of 700 nm to 750 nm. Among these, the light emitting diodes A to O are examples of the present invention, and the light emission output is 10.1 to 10.8 [a. u. ] Is high. On the other hand, the light emitting diodes P to Z are comparative examples, and the light emission output is 6.2 to 8.4 [a. u. ] And low. The semiconductor layer (p-type AlGaAs cladding layer 4, p-type AlGaAs active layer 5, n-type AlGaAs cladding layer 6) immediately below the SiO insulating film (second insulating film) 19 has a general formula of Al _x Ga _1-x As ( 0.5 ≦ x ≦ 0.8).

  Focusing on the thickness of the SiO insulating film (first insulating film) 11 in this embodiment, the light-emitting diode arrays A, B, and C have a thickness of the first insulating film of 30 nm or less, and the light-emitting diode arrays D, E and F have a first insulating film thickness of 35 nm or less, the light emitting diode arrays G, H, and I have a first insulating film thickness of 40 nm or less, and the light emitting diode arrays J, K, and L have the first thickness. Since the film thickness of the insulating film is 45 nm or less, and the light emitting diode arrays M, N, and O have the film thickness of the first insulating film of 50 nm or less, they can be grouped as an index.

  As apparent from the values of the film thickness of the SiO insulating film (first insulating film) 11, the SiN protective film 14, the SiO insulating film (second insulating film) 19 and the emission peak wavelength shown in Table 1, the light emitting diode array A , B and C are the light emitting diode arrays according to claim 1.

  That is, the light emitting diode arrays A, B, and C have an emission wavelength in the range of 700 to 750 nm (specifically, 723 nm to 727 nm), and the thickness of the SiO insulating film (first insulating film) 11 is 30 nm or less ( Specifically, when the film thickness of the protective film is d1 (unit nm) and the film thickness of the second insulating film is d2 (unit nm), (d1, d2) (647, 421), (650, 392), (660, 366), (670, 365), (680, 368), (690, 371), (700, 375), (710, 381), (720, 391), (730, 416), (730, 428), (710, 475), (700, 486), (690, 493), (680, 497), (670, 496), (660 , 491), (647, 464), (64 It has become an arbitrary value within the closed region (3) connecting sequentially linearly each point 421).

  Similarly, the light emitting diode arrays D, E, and F are respectively the light emitting diode array according to claim 2, and the light emitting diode arrays G, H, and I are respectively the light emitting diode array, light emitting diode arrays J, K, and L is the light-emitting diode array according to claim 4, and light-emitting diode arrays M, N, and O are the light-emitting diode array according to claim 5, respectively.

  The light emitting diode arrays D, E, and F of claim 2 have an emission wavelength in a range of 700 nm to 750 nm (specifically, 726 nm), and a thickness of the SiO insulating film (first insulating film) 11 is 35 nm or less ( Specifically, when the thickness of the protective film is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) Are (646, 436), (650, 408), (660, 385), (670, 378), (680, 378), (690, 380), (700, 384), (710, 392), (719, 412), (719, 432), (710, 458), (700, 473), (690, 483), (680, 488), (670, 490), (660, 487), (650) 477), (646, 462), (646, 4 Closed region connecting sequentially linearly each point 6) (which is an arbitrary value of FIG. 4) within.

  The light emitting diode arrays G, H, and I according to claim 3 have an emission wavelength in the range of 700 nm to 750 nm (specifically, 723 nm to 725 nm), and the thickness of the SiO insulating film (first insulating film) 11 is 40 nm. (Specifically, 36.7 to 39.2 nm), when the protective film thickness is d1 (unit nm) and the second insulating film thickness is d2 (unit nm), (d1, d2) is (646, 439), (650, 417), (660, 395), (670, 388), (680, 386), (690, 389), (700, 395), (709, 414). ), (709, 430), (700, 456), (690, 470), (680, 479), (670, 483), (660, 482), (650, 474), (646, 462), Closure of connecting points (646, 439) in sequence with straight lines It is an arbitrary value in the region (FIG. 5).

  The light emitting diode arrays J, K, and L of claim 4 have an emission wavelength in a range of 700 nm to 750 nm (specifically, 725 nm to 728 nm), and a thickness of the SiO insulating film (first insulating film) 11 is 45 nm. (Specifically, 40.7 to 44.0 nm), when the thickness of the protective film is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 447), (650, 424), (660, 404), (670, 397), (680, 395), (690, 399), (699, 416), (699, 429). ), (690, 454), (680, 467), (670, 474), (660, 475), (650, 469), (646, 455), (646, 447) in a straight line. It is an arbitrary value within the closed region to be connected (FIG. 6).

  The light emitting diode array M, N, and O of claim 5 has an emission wavelength in the range of 700 nm to 750 nm (specifically, 724 nm to 728 nm), and the thickness of the SiO insulating film (first insulating film) 11 is 50 nm. (Specifically, 46.4 to 48.5 nm), when the thickness of the protective film is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (648, 442), (650, 432), (660, 412), (670, 405), (680, 406), (688, 417), (688, 433), (680, 452). ), (670, 463), (660, 467), (650, 461), (648, 455), (648, 442), any value within the closed region (FIG. 7) that sequentially connects the points. It has become.

  On the other hand, the light-emitting diode arrays P to Z do not correspond to any one of claims 1 to 5 and are light-emitting diode arrays not corresponding to the present invention.

  As apparent from the values of the light emission outputs in Table 1, the light emitting diode arrays A to O according to the present invention have a light emission output larger than that of the light emitting diode arrays P to Z that do not fall under the present invention, approximately 20%. The above improvement in light emission output is recognized.

  The effects of the present invention could be confirmed by the above examples.

<Other embodiments and modifications>
In the above embodiment, the description has been made by taking the semiconductor crystal structure for light emitting diodes in the order of p-type and n-type with the p-type semiconductor crystal on the semi-insulating GaAs substrate 1 as the crystal structure. The present invention can also be applied to a semiconductor crystal structure for light emitting diodes in the order of n-type and p-type with an n-type semiconductor crystal placed on a conductive GaAs substrate 1. An effect of improving the external luminous efficiency can be obtained.

  In the above embodiment, the semi-insulating GaAs substrate is used as the substrate. However, even if the substrate is a conductive substrate, a high resistance layer such as undoped GaAs is provided on the substrate, or pnp or n If the structure becomes -pn, it can be electrically insulated and thus can be applied in the same manner.

<Usage method, application system, etc.>
The light emitting diode array according to the present invention can be applied to a light emitting diode array used for an electrophotographic printer light source.

It is a top view of the light emitting diode array which shows one Embodiment of this invention. It is a structure sectional view of the light emitting diode array which shows one embodiment of the present invention. It is the figure which showed the appropriate range of the film thickness d1 of a protective film, and the film thickness d2 of a 2nd insulating film about the light emitting diode array A, B, C which concerns on the Example of this invention. It is the figure which showed the appropriate range of the film thickness d1 of a protective film, and the film thickness d2 of a 2nd insulating film about the light emitting diode arrays D, E, and F which concern on the Example of this invention. It is the figure which showed the appropriate range of the film thickness d1 of a protective film, and the film thickness d2 of a 2nd insulating film about the light emitting diode arrays G, H, and I which concern on the Example of this invention. It is the figure which showed the appropriate range of the film thickness d1 of a protective film, and the film thickness d2 of a 2nd insulating film about the light emitting diode arrays J, K, and L which concern on the Example of this invention. It is the figure which showed the appropriate range of the film thickness d1 of a protective film, and the film thickness d2 of a 2nd insulating film about the light emitting diode array M, N, and O which concern on the Example of this invention. It is a top view of the conventional light emitting diode array. It is a structure sectional view of the conventional light emitting diode array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semi-insulating GaAs substrate 2 p-type GaAs conductive layer 3 p-type AlGaAs etching stopper layer 4 p-type AlGaAs cladding layer 5 p-type AlGaAs active layer 6 n-type AlGaAs cladding layer 7 n-type GaAs cap layer 8 Cathode contact electrode 9 n Part of type GaAs cap layer 10 Light-emitting diode part 11 First insulating film (SiO insulating film)
12 light emitting part 12a light emitting part surface 13 mesa etching groove 14 protective film (SiN protective film)
15 Contact electrode for anode 16 Au wiring 17 Bonding pad for cathode 18 Bonding pad for anode 19 Second insulating film (SiO insulating film)

Claims (5)

In a light-emitting diode array in which a plurality of compound semiconductor layers are epitaxially grown on a substrate and have a plurality of light-emitting diode parts that are insulated and divided, and the light-emitting part surface of the light-emitting diode part is covered with a protective film made of an insulating film.
The emission wavelength is in the range of 700 nm to 750 nm,
And the protective film is formed of a second insulating film made of silicon oxide, a protective film made of silicon nitride, and a first insulating film made of silicon oxide sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 30 nm or less,
When the thickness of the protective film made of silicon nitride (SiN) is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (647, 421). ), (650, 392), (660, 366), (670, 365), (680, 368), (690, 371), (700, 375), (710, 381), (720, 391), (730, 416), (730, 428), (710, 475), (700, 486), (690, 493), (680, 497), (670, 496), (660, 491), (647) 464), (647, 421), which is an arbitrary value within a closed region that sequentially connects the points with a straight line. In a light-emitting diode array in which a plurality of compound semiconductor layers are epitaxially grown on a substrate and have a plurality of light-emitting diode portions insulated and divided, and the light-emitting surface of the light-emitting diode portion is covered with a protective film made of an insulating film.
The emission wavelength is in the range of 700 nm to 750 nm,
And the protective film is formed of a second insulating film made of silicon oxide, a protective film made of silicon nitride, and a first insulating film made of silicon oxide sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 35 nm or less,
When the thickness of the protective film made of silicon nitride is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 436), ( 650, 408), (660, 385), (670, 378), (680, 378), (690, 380), (700, 384), (710, 392), (719, 412), (719, 432), (710, 458), (700, 473), (690, 483), (680, 488), (670, 490), (660, 487), (650, 477), (646, 462) , (646, 436) is an arbitrary value within a closed region that sequentially connects the points with a straight line. In a light-emitting diode array in which a plurality of compound semiconductor layers are epitaxially grown on a substrate and have a plurality of light-emitting diode portions insulated and divided, and the light-emitting surface of the light-emitting diode portion is covered with a protective film made of an insulating film.
The emission wavelength is in the range of 700 nm to 750 nm,
And the protective film is formed of a second insulating film made of silicon oxide, a protective film made of silicon nitride, and a first insulating film made of silicon oxide sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 40 nm or less,
When the thickness of the protective film made of silicon nitride is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 439), ( 650, 417), (660, 395), (670, 388), (680, 386), (690, 389), (700, 395), (709, 414), (709, 430), (700, 456), (690, 470), (680, 479), (670, 483), (660, 482), (650, 474), (646, 462), (646, 439) in a straight line. A light emitting diode array characterized by being an arbitrary value in a closed region connected by. In a light-emitting diode array in which a plurality of compound semiconductor layers are epitaxially grown on a substrate and have a plurality of light-emitting diode portions insulated and divided, and the light-emitting surface of the light-emitting diode portion is covered with a protective film made of an insulating film.
The emission wavelength is in the range of 700 nm to 750 nm,
And the protective film is formed of a second insulating film made of silicon oxide, a protective film made of silicon nitride, and a first insulating film made of silicon oxide sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 45 nm or less,
When the thickness of the protective film made of silicon nitride is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (646, 447), ( 650, 424), (660, 404), (670, 397), (680, 395), (690, 399), (699, 416), (699, 429), (690, 454), (680, 467), (670, 474), (660, 475), (650, 469), (646, 455), (646, 447) must be any value within the closed region that sequentially connects the points. A light emitting diode array. In a light-emitting diode array in which a plurality of compound semiconductor layers are epitaxially grown on a substrate and have a plurality of light-emitting diode parts that are insulated and divided, and the light-emitting part surface of the light-emitting diode part is covered with a protective film made of an insulating film.
The emission wavelength is in the range of 700 nm to 750 nm,
And the protective film is formed of a second insulating film made of silicon oxide, a protective film made of silicon nitride, and a first insulating film made of silicon oxide sequentially from the outermost surface,
In addition, the semiconductor layer immediately below the second insulating film is formed of a compound semiconductor represented by the general formula Al _x Ga _1-x As (0.5 ≦ x ≦ 0.8),
And the thickness of the first insulating film is 50 nm or less,
When the thickness of the protective film made of silicon nitride is d1 (unit: nm) and the thickness of the second insulating film is d2 (unit: nm), (d1, d2) is (648, 442), ( 650, 432), (660, 412), (670, 405), (680, 406), (688, 417), (688, 433), (680, 452), (670, 463), (660, 467), (650, 461), (648, 455), (648, 442), which is an arbitrary value in a closed region that sequentially connects the points with a straight line.

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