JP2009032985A - Semiconductor luminous element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high luminous efficacy-semiconductor luminous element that is an InGaN system element of high In-composition having a uniform composition distribution and a method for manufacturing the same. <P>SOLUTION: A semiconductor laser diode 10 is provided with a ZnO substrate 12, a pseudo-lattice matching layer 13, a lower clad layer 14, a light guide layer 21, an active layer 15, a light guide layer 22, an upper clad layer 16, and a contact layer 17 sequentially formed on the substrate. An epitaxial wafer of the semiconductor laser diode 10 is formed on a c-surface (000_1) ZnO substrate 12 of oxygen (O) polarity. The pseudo-lattice matching layer 13 formed between the substrate and the active layer 15 is composed of GaN with film thickness of 1ML (molecular layer) or more and critical film thickness or less to the ZnO substrate 12. The diffusion of Ga in the active layer 15 is suppressed in the ZnO substrate to obtain a steep interface between the ZnO substrate and active layer, thus enabling the system to get excellent crystal in the active layer composed of InGaN. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device including a ZnO single crystal substrate and a device including a nitride semiconductor layer formed by growing on the substrate, and a method for manufacturing the same.

  Conventionally, a semiconductor light emitting device using InGaN as a semiconductor light emitting device emitting blue light (emission wavelength of 480 nm or less) is known (for example, see Patent Document 1).

By the way, in order to obtain longer wavelength green light emission with this semiconductor light emitting device using InGaN, it is conceivable to narrow the forbidden band width of the active layer by increasing the In composition ratio.
Japanese Patent Laid-Open No. 06-061527 MRSIJ vol1, Article16,1996

  However, when the In composition ratio is increased, phase separation occurs, and it becomes difficult to obtain an active layer having a uniform In composition, resulting in a decrease in luminous efficiency. Further, when a piezoelectric field is generated due to the crystal structure, there is a problem that the light emission recombination probability is lowered and the light emission efficiency is further lowered. In addition, since the lattice constant differs greatly from that of the substrate, there are a large number of threading dislocations, and there is a problem that the light emission efficiency is lowered and good reliability cannot be obtained.

In order to suppress these, it is possible to use a substrate that is lattice-matched (close to the lattice constant) to an active layer of a nitride semiconductor such as InGaN or a clad layer that is close to the lattice constant. A ZnO single crystal substrate is suitable as the substrate. However, when a nitride semiconductor such as InGaN is grown on a ZnO single crystal substrate, it grows in an atmosphere using ammonia (NH ₃ ), and zinc oxide ZnO sublimates at 750 ° C or higher. was there.

In addition, when a GaN layer is directly grown on a ZnO single crystal substrate, there is a problem that the interface between the ZnO single crystal substrate and the GaN layer reacts, and the sharpness of the interface cannot be obtained, and a good crystal cannot be obtained. (e.g., see non-Patent Document 1 Ga ₂ ZnO ₄ is formed).

  In addition, when an InGaN layer is directly grown on a ZnO single crystal substrate, formation of a complicated interface layer by the above-described interface reaction, or into a ZnO substrate as shown in FIGS. Local diffusion of Ga was observed, and an InGaN layer with a good crystal could not be obtained.

  The present invention has been made in view of such a conventional problem, and an object thereof is a high-In composition InGaN-based device having a uniform composition distribution, and a semiconductor light-emitting device having high luminous efficiency and It is in providing the manufacturing method.

First, the outline | summary of the means for solving the said subject is demonstrated.
The reason why an InGaN layer having good crystallinity cannot be obtained is that Ga diffuses in the ZnO single crystal substrate and the interface steepness cannot be obtained. The diffusion of Ga into the ZnO single crystal substrate is due to the fact that the surface of the ZnO single crystal substrate is not flat and the impurities in the chemical mechanical polishing are not completely removed. For example, sublimation.

Therefore, the following four means can be cited for planarizing the substrate surface.
(a) Perform high-temperature heat treatment (1000-1300 ° C, 1-5 hours) in a box made of ZnO sintered body.
(b) Use an oxygen (O) polar surface that can obtain a flatter surface by this heat treatment.
(c) Before the growth, heat treatment (1000 ° C., 30 minutes) is performed in a vacuum chamber, in vacuum, in oxygen, or with oxygen plasma irradiation.
(d) A ZnO buffer layer is epitaxially grown on the ZnO substrate.

In addition, since Ga ₂ ZnO ₄ is formed when grown at high temperatures, it can be formed on a ZnO substrate by MBE, PLD, and MOCVD growth using nitrogen plasma that can be grown at a low temperature of 750 ° C. or lower without using ammonia. Growing nitride semiconductor.

  This is due to the difference in the adsorption coefficient of In and Ga on the surface of the ZnO substrate. In has a smaller adsorption coefficient than Ga, and when InGaN is grown, In tends to segregate on the surface, and In drops appear on the surface. It is easy to form, and an In surface excess layer is formed, and the sum of the energy of the interface between the ZnO single crystal substrate and the InGaN growth layer and the energy of the InGaN growth layer is larger than the surface energy of the ZnO single crystal substrate. In addition, since the substrate is exposed to lower energy, a so-called Volumer-Weber (VW) growth mode appears in which a three-dimensional island appears from the start of growth. Therefore, a GaN layer, which is a binary material not containing In, is first grown on the ZnO substrate. Alternatively, an InN layer that is a binary material containing no Ga is grown. At that time, in order to maintain the lattice constant of the ZnO substrate at the top, the film thickness is set to 1 ML or more and the critical film thickness or less.

Next, means for solving the above problems will be specifically described below.
The semiconductor light emitting device according to the first aspect of the present invention includes a ZnO single crystal substrate, an active layer made of gallium indium nitride [In x Ga 1-x N (0 <x <1)], and the ZnO single crystal substrate. Formed on the upper cladding layer, a pseudo-lattice matching layer formed between the active layer and the active layer, upper and lower cladding layers lattice-matched to at least one of the active layer or the ZnO single crystal substrate, and And a contact layer formed on the substrate.

  According to this aspect, since the pseudo lattice matching layer is formed between the ZnO single crystal substrate and the active layer, a steep nitride / oxide interface is obtained between the ZnO single crystal substrate and the active layer, Good crystals of the active layer made of InGaN are obtained. As a result, a highly reliable semiconductor light emitting device with high luminous efficiency can be obtained.

  In addition, by using a ZnO single crystal substrate, even if an InGaN active layer having a high In composition ratio, which is necessary for realizing a light emitting device with visible light having a wavelength longer than blue (for example, green), is generated by a piezoelectric field. As a result, the phase separation of Ga and In and threading dislocations can be suppressed, so that a semiconductor light emitting device capable of obtaining long wavelength green light emission can be realized with a high In composition InGaN system having a uniform composition distribution.

  The semiconductor light emitting device according to another aspect of the present invention is characterized in that the pseudo lattice matching layer is made of GaN having a thickness of one molecular layer (1 ML) or more and a critical thickness or less with respect to the substrate.

  According to this aspect, by configuring the pseudo lattice matching layer with thin GaN having a film thickness of 1 ML or more and a critical film thickness or less with respect to the substrate, the lattice constant of the underlying ZnO single crystal substrate is maintained, An active layer made of InGaN lattice-matched with the ZnO single crystal substrate is grown on the upper portion, thereby obtaining an active layer having a good crystal.

  The semiconductor light emitting device according to another aspect of the present invention is characterized in that the pseudo-lattice matching layer is made of a superlattice.

  In the semiconductor light emitting device according to another aspect of the present invention, the pseudo lattice matching layer made of a superlattice is a super lattice layer made of GaN and InN having a thickness of 1 ML or more and a critical thickness or less with respect to the substrate. It is characterized by.

  According to this aspect, the lattice constant of the underlying ZnO single crystal substrate is formed by configuring the pseudo-lattice matching layer with a superlattice layer composed of GaN and InN having a thickness of 1 ML or more and a critical thickness or less with respect to the substrate. While maintaining the above, an active layer made of InGaN lattice-matched with the ZnO single crystal substrate is grown on the upper portion to obtain an active layer having a good crystal.

  Further, the thickness of the entire pseudo-lattice matching layer can be made thicker than when the pseudo-lattice matching layer is made of GaN having a thickness of 1 ML or more and a critical thickness or less with respect to the substrate. This makes it difficult for impurities from the base to reach the active layer made of InGaN, and an active layer having better crystals can be obtained.

  In the semiconductor light emitting device according to another aspect of the present invention, the lower clad layer is made of zinc magnesium beryllium cadmium [Zn 1-abc MgABeb Cd c O (0 ≦ a <1, 0 ≦ b <1, 0 ≦ c < 1, a + b + c ≦ 1)].

  The semiconductor light emitting device according to another aspect of the present invention is characterized in that the lower clad layer is zinc oxide.

  In the semiconductor light emitting device according to another aspect of the present invention, the lower clad layer is aluminum gallium indium nitride [Al 1 -pq Ga p In q N (0 ≦ p <1, 0 ≦ q <1, p + q ≦ 1)]. It is characterized by being.

The semiconductor light emitting device according to another aspect of the present invention is characterized in that in the active layer, the composition ratio of indium (In) is set so that the emission wavelength is 480 nm or more. The emission wavelength is set to be 480 nm or more and 650 nm or less. According to this aspect, it is possible to realize a semiconductor laser diode capable of emitting visible light (for example, green) having a wavelength longer than blue.

  The semiconductor light emitting device according to another aspect of the present invention is characterized in that the composition ratio of indium (In) is 20% or more.

  A semiconductor light emitting device according to another aspect of the present invention is characterized in that a light guide layer is provided between the active layer and the cladding layer.

  According to this aspect, the light guide layer can stably and efficiently confine light in the central active layer functioning as the core.

  A semiconductor light emitting device according to another aspect of the present invention is characterized in that a buffer layer made of ZnO is formed between the ZnO single crystal substrate and the active layer.

  According to this aspect, since the buffer layer surface with good flatness can be formed, an active layer made of InGaN having better crystals can be formed by growing an active layer made of InGaN lattice-matched with the ZnO single crystal substrate on the upper surface. Is obtained.

  In order to solve the above-described problem, a method for manufacturing a semiconductor light emitting device according to a second aspect of the present invention includes a substrate surface treatment step of using a ZnO single crystal substrate to modify the surface of the ZnO single crystal substrate, A lower clad layer forming step of forming a lower clad layer lattice-matched to at least one of the ZnO single crystal substrate and the active layer, and gallium indium nitride [Inx Ga1-x N (0 <x <1) on the lower clad layer An active layer forming step for forming an active layer, a pseudo lattice matching layer forming step for forming a pseudo lattice matching layer between the ZnO single crystal substrate and the active layer, and the ZnO single crystal substrate or the active layer. An upper clad layer forming step for forming an upper clad layer lattice-matched to at least one of the layers on the active layer; and a contact layer forming step for forming a contact layer on the upper clad layer. To.

  According to this aspect, since the pseudo lattice matching layer is formed between the ZnO single crystal substrate and the active layer made of gallium indium nitride, the steep nitride / oxide between the ZnO single crystal substrate and the active layer is formed. An interface is obtained, and a good crystal of the active layer made of InGaN is obtained. As a result, a highly reliable semiconductor light emitting device with high luminous efficiency can be obtained.

  In addition, by using a ZnO single crystal substrate, even if an active layer made of InGaN having a high In composition ratio necessary for realizing a light-emitting device in the green region is used, the influence of the piezoelectric field, phase separation, and threading dislocation are reduced. Therefore, it is possible to realize a semiconductor laser diode capable of emitting visible light (for example, green) having a wavelength longer than that of blue, using an InGaN system with a high In composition having a uniform composition distribution.

  In the method of manufacturing a semiconductor light emitting device according to another aspect of the present invention, the pseudo lattice matching layer forming step includes forming the pseudo lattice matching layer into a GaN layer having a thickness of 1 ML or more and a critical thickness or less with respect to the ZnO substrate. It is characterized by forming in.

  According to this aspect, by configuring the pseudo lattice matching layer with thin GaN having a film thickness of 1 ML or more and a critical film thickness or less with respect to the substrate, the lattice constant of the underlying ZnO single crystal substrate is maintained, An active layer made of InGaN lattice-matched with the ZnO single crystal substrate is grown on the upper portion, thereby obtaining an active layer having a good crystal.

  The method of manufacturing a semiconductor light emitting device according to another aspect of the present invention is characterized in that the pseudo lattice matching layer forming step uses nitrogen plasma to grow at a low temperature.

  In the method of manufacturing a semiconductor light emitting device according to another aspect of the present invention, the pseudo lattice matching layer forming step includes performing heat treatment in a vacuum, an oxygen atmosphere, or oxygen plasma irradiation before forming the pseudo lattice matching layer. It is characterized by.

  The method of manufacturing a semiconductor light emitting device according to another aspect of the present invention is characterized in that the pseudo lattice matching layer is formed on an oxygen (O) polar c-plane (000_1) of the ZnO single crystal substrate.

  According to this aspect, the pseudo-lattice matching layer is formed on the c-plane (000_1) of the oxygen (O) polarity of the ZnO single crystal substrate, thereby planarizing the surface of the ZnO single crystal substrate, that is, chemical mechanical polishing. By performing the heat treatment, a clean surface with good flatness can be obtained on the oxygen (O) polar c-plane. Thereby, a steep nitride / oxide interface between the ZnO single crystal substrate and the active layer is obtained, and a better crystal of the active layer made of InGaN is obtained. As a result, a highly reliable semiconductor light emitting device with high luminous efficiency can be obtained.

  According to the present invention, an InGaN-based element having a uniform composition distribution and a high In composition, which has a high light emission efficiency and a high reliability, can be realized.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the description of each embodiment, the same parts are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
A semiconductor laser diode 10 as a semiconductor light emitting device according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a schematic configuration of a semiconductor laser diode 10 according to the first embodiment.

  As shown in FIG. 1, the semiconductor laser diode 10 includes a ZnO single crystal substrate 12, a pseudo lattice matching layer 13, a lower clad layer 14, a light guide layer 21, and an active guide layer formed on the ZnO single crystal substrate 12 in this order. A layer 15, a light guide layer 22, an upper cladding layer 16, and a contact layer 17. The semiconductor laser diode 10 further includes a lower electrode layer 11 formed on the back side of the ZnO single crystal substrate 12, a passivation film 18, and an upper electrode layer 19.

  In this semiconductor laser diode 10, an epitaxial wafer for a semiconductor laser diode, which is formed on a ZnO single crystal substrate 12 and emits light in a long-wavelength visible region such as a green region, includes a pseudo lattice matching layer 13, a lower cladding layer 14, a light The guide layer 21, the active layer 15, the light guide layer 22, the upper cladding layer 16, and the contact layer 17 are configured. In the present embodiment, the epitaxial wafer is formed on a c-plane (000_1) ZnO single crystal substrate 12 having an oxygen (O) polarity.

  The pseudo-lattice matching layer 13 formed between the ZnO single crystal substrate (hereinafter referred to as ZnO substrate) 12 and the active layer 15 has a thickness of 1 ML (molecular layer) or more and a critical thickness relative to the ZnO substrate 12. It consists of the following GaN. The pseudo lattice matching layer 13 has n-type conductivity by doping silicon (Si).

  The “critical film thickness” here is obtained by calculating how much film thickness can be grown on the lower ZnO substrate 12 (see FIG. 3). From FIG. 2, the critical film thickness of the pseudo lattice matching layer 13 made of GaN is about 20 nm at the maximum. Note that since the critical film thickness forms the active layer 15 made of InGaN on the upper surface, considering the layer formed on the pseudo lattice matching layer, the critical film thickness of the pseudo lattice matching layer 13 made of GaN is 50 nm. It can be as thick as possible. Thus, the critical film thickness of the pseudo lattice matching layer 13 made of GaN can be set within a range of 1 ML or more and 50 nm or less, and is preferably set within a range of 1 ML or more and about 20 nm or less.

  The lower cladding layer 14 is a lattice-matched cladding layer that is lattice-matched to at least one of the active layer 15 or the ZnO substrate 12. The lower cladding layer 14 is formed by growing Al (Ga) InN lattice-matched to at least one of the active layer 15 or the ZnO substrate 12 on the pseudo-lattice matching layer 13. Here, the lower cladding layer 14 has n-type conductivity by doping silicon (Si).

  The light guide layer 21 is formed by growing an InGaN crystal on the lower cladding layer 14. The light guide layer 21 has n-type conductivity by supplying silicon (Si).

  The active layer 15 is formed by growing a gallium indium [In x Ga 1-x N (0 <x <1)] crystal (InGaN layer) on the light guide layer 21. In the active layer 15, the composition ratio of indium (In) is set so that the emission wavelength is 480 nm or more. Specifically, the active layer 15 is composed of an InGaN layer having an In composition (In composition ratio of 20% or more) having an emission wavelength in the green region. In this example, the In composition ratio in the InGaN layer is about 30%.

  The light guide layer 22 is formed by growing an InGaN crystal on the active layer 15. The light guide layer 22 has p-type conductivity by doping with magnesium (Mg).

  The upper cladding layer 16 is formed by growing Al (Ga) InN lattice-matched to at least one of the active layer 15 or the ZnO substrate 12 on the light guide layer 22. Here, the upper cladding layer 14 has p-type conductivity by doping with magnesium (Mg).

  The contact layer 17 is formed on the upper clad layer 16 by supplying N onto the substrate together with Ga and In materials set to the optimum cell temperature. The contact layer 17 has p-type conductivity by supplying magnesium (Mg). That is, the contact layer is p-type doped.

  The characteristics of the semiconductor laser diode 10 according to the first embodiment having such a configuration are as follows.

A ZnO (zinc oxide) substrate 12 is used.
A pseudo lattice matching layer 13 formed between the ZnO substrate 12 and the active layer 15 is provided.
The pseudo lattice matching layer 13 is made of GaN having a film thickness of 1 ML (molecular layer) or more and a critical film thickness or less with respect to the ZnO substrate 12.

Next, a method for manufacturing the semiconductor laser diode 10 having the above configuration will be described.
In the present embodiment, the above-described epitaxial wafer for a semiconductor laser diode that emits light in a long-wavelength visible region such as a green region is subjected to an oxygen (O) polarity c-plane (000_1) using the RFMBE method by the following steps. It is formed on the ZnO substrate 12.
(Step 1) First, a ZnO substrate 12 is prepared, and a surface treatment is performed on the ZnO substrate 12. As this surface treatment, the following surface flattening treatment, surface cleaning treatment, and surface modification treatment are performed.

  (Step 1a) In the surface flattening process, first, the CMP (mechanical chemical polishing) process of the ZnO substrate 12 is performed, and then the oxygen (O) polar c-plane (000_1) ZnO substrate 12 is heat-treated in the air. To form a step-and-terrace structure. In this case, it is preferable to carry out in a state of being sandwiched between flat plates of an inorganic material such as zirconia oxide or zinc oxide. The heat treatment conditions are preferably a temperature of 1000-1300 ° C. and 1-5 hours. After this surface flattening treatment, molybdenum (Mo), which is a refractory metal, is deposited on the back surface of the oxygen (O) polar c-plane (000_1) ZnO substrate 12 by sputtering, EB method or the like and then introduced into the growth chamber. .

  (Step 1b) In the surface cleaning process, a thermal cleaning process is performed under atmospheric pressure or reduced pressure in the growth chamber. Specifically, the ZnO substrate 12 is heated for 30 to 60 minutes in a vacuum at a temperature of 700 to 750 ° C. to remove organic substances and the like.

  Alternatively, a streak pattern is observed by RHEED measurement due to cleaning of the ZnO substrate 12 and surface reconstruction of the ZnO substrate 12 by performing high-temperature heat treatment at 1000 ° C. for 30 minutes as thermal cleaning processing conditions. It is preferably performed in an oxygen atmosphere or oxygen plasma irradiation.

  (Step 1c) In the surface modification process performed after the surface cleaning process, a nitridation process is performed in order to form the pseudo lattice matching layer 13 made of GaN as a nitride on the ZnO substrate 12. Specifically, a nitrogen plasma is supplied at a substrate temperature of 500 ° C. for 30 to 60 minutes with a nitrogen plasma gun, and the surface of the ZnO substrate 12 is substituted with nitrogen to be deposited on the upper surface by replacing the oxygen with nitrogen. To do.

  (Step 2) Next, by simultaneously supplying Ga and nitrogen radical (N) to the substrate surface at a temperature lower than 750 ° C., for example, about 500 ° C., an oxygen (O) polar c-plane (000_1) ZnO substrate A GaN crystal is grown on the layer 12 by 4 ML to form the pseudo lattice matching layer 13.

  The reason why the growth temperature of the GaN crystal is low is to suppress the interface reaction between the ZnO substrate 12 and the pseudo lattice matching layer 13 made of GaN. Here, after growing 4ML of GaN, grow 1ML of InN, grow 1ML of InN and then grow 4ML of GaN, or grow a layer in which GaN layers and InN layers are stacked alternately to grow a pseudo lattice The matching layer 13 may be formed.

  The lattice constant difference between ZnO and GaN is about 1.8% in the a-axis, and the lattice constant difference between ZnO and InN is about 8.8% in the a-axis, respectively, but the GaN layer and the InN layer constituting the pseudo lattice matching layer 13 are different. The lattice constant of ZnO can be maintained by setting the total film thickness to be equal to or less than the critical thickness of InGaN obtained by taking the average composition of the GaN layer and InN layer. Here, the pseudo lattice matching layer 13 having n-type conductivity is formed by doping the pseudo lattice matching layer 13 with silicon (Si).

Further, after growing a GaN crystal at a low temperature of about 500 ° C., a heat treatment is performed at a temperature of 700-1000 ° C. for 30 minutes to 2 hours to crystallize the pseudo lattice matching layer 13 made of a GaN thin film deposited at a low temperature. The streak pattern appears gradually. Thereby, the crystallinity of the layer formed on the upper part of the pseudo lattice matching layer 13 made of GaN can be improved. If the temperature for growing the GaN crystal is too high, Ga diffuses into ZnO and Ga ₂ ZnO ₄ is formed, so it is necessary to set the temperature optimally (crystallization of the pseudo lattice matching layer 13).

  (Step 3) Next, the growth temperature is set to a temperature lower than 750 ° C., for example, 450 ° C., and In, Ga and Al which are raw materials set to a desired cell temperature are supplied onto the ZnO substrate 12 together with N. By doing so, AlGaInN lattice-matched to at least one of the active layer 15 or the ZnO substrate 12 is grown to form the lower cladding layer 14. Since this InGaN crystal is grown on the c-plane ZnO substrate 12, the lattice constant of the a axis may be matched. At this time, the lower cladding layer 14 can be made n-type conductive by doping silicon (Si).

  Thus, in the present embodiment, the lower cladding layer 14 is aluminum gallium indium nitride [Al 1-p-q Ga p In q N (0 ≦ p <1, 0 ≦ q <1, p + q ≦ 1)]. The lower clad layer 14 is replaced with Al (Ga) InN, zinc magnesium beryllium cadmium [Zn 1-abc Mg aBeb Cd c O (0 ≦ a <1, 0 ≦ b <1, 0 ≦ c <1 , A + b + c ≦ 1)], or zinc oxide.

  (Step 4) Next, an InGaN crystal is grown by supplying In in addition to Ga and N while keeping the growth temperature lower than 750 ° C., for example, 450 ° C., and the light guide layer is formed on the lower cladding layer 14. 21 is formed. At this time, a good InGaN crystal can be grown by setting the In composition of the InGaN layer between the In composition of the lower cladding layer and the active layer. At this time, by supplying silicon (Si) to the light guide layer 21 made of InGaN, the light guide layer 21 can be made to be n-type conductive.

  (Step 5) Next, change the cell temperature setting so that the growth temperature remains lower than 750 ° C., for example, 450 ° C., so that the optimal In / Ga ratio and V / III ratio are obtained (or a plurality of If you have a cell, switch to the preset In and Ga cells), and supply it to the substrate with N, so that the In composition (about 30%) with the emission wavelength in the green region An active layer 15 made of InGaN is formed.

  (Step 6) Next, the light guide layer 22 made of InGaN with an In composition between the active layer and the In composition of the upper cladding layer is formed on the active layer 15 again at a growth temperature lower than 750 ° C., for example, 450 ° C. To do. At this time, change the cell temperature settings to achieve the optimal In / Ga ratio and V / III ratio (or if you have multiple cells, set the In and Ga cells that have been set in advance) The light guide layer 22 made of InGaN is formed by supplying to the substrate together with N. At this time, the light guide layer 22 can be made to have p-type conductivity by doping InGaN with magnesium (Mg).

  (Step 7) Next, by supplying In, Ga and Al, which are raw materials set at a desired cell temperature, at a growth temperature lower than 750 ° C., for example, 450 ° C., together with N, the active layer The upper cladding layer 16 is formed by growing Al (Ga) InN lattice-matched to at least one of the 15 or the ZnO substrate 12 (or the light guide layer 22 made of the ZnO substrate 12 and InGaN). At this time, the upper cladding layer 16 can be made p-type conductive by doping with magnesium (Mg).

  (Step 8) Finally, the contact layer 17 is formed by supplying N onto the substrate together with the Ga and In materials set to the optimum cell temperature. At this time, p-type conductivity can be achieved by simultaneously supplying Mg.

  In the above step, beryllium Be, magnesium Mg and silicon Si (co-doped), or the like can be used as the p-type dopant instead of magnesium (Mg) (p-type co-doping).

In addition, after the epi-growth, the Mg-doped layer can be made p-type conductive by activating Mg by performing a heat treatment at a high temperature after taking out from the growth chamber or from a vacuum ( Mg activation heat treatment).
Through the above steps 1 to 8, an epitaxial wafer for the semiconductor laser diode 10 that emits light in a long-wavelength visible region such as a green region is manufactured.
Next, a procedure for manufacturing a laser diode structure of the semiconductor laser diode 10 using the epitaxial wafer manufactured as described above will be described.

(Step 9) Next, a ridge structure is formed.
The ridge structure is a kind of semiconductor laser diode structure, and can realize an actual refractive index waveguide structure that can reduce the loss of light in the optical waveguide. Although it is a relatively simple structure, precise control of the processing technique is required to keep the oscillation state of the laser light stable. Specifically, a ridge structure is formed by photolithography and dry etching techniques.

(Step 10) Next, a passivation film 18 is formed.
The passivation film 18 functions as a protective layer, and SiO ₂ and ZrO ₂ are made of PCVD (Plasma
Chemical Vapor Deposition) is used for deposition.

(Step 11) Next, the upper electrode layer 19 is formed. Here, consider the case where the contact layer 17 has p-type conductivity.
Specifically, an electrode pattern is formed by photolithography, the passivation film 18 is removed, electrode metal is deposited by resistance heating, EB (electron beam) or sputtering, and then sintered (sintering). For example, a Ni / Au or Pd / Pt / Au electrode is formed as the p-type upper electrode layer 19. In this case, the formed p-type upper electrode layer 19 is in ohmic contact with the p-type contact layer 17.

  (Step 12) Next, the lower electrode layer 11 is formed on the back side of the epitaxial wafer for a long-wavelength visible laser diode such as the green region described above. Here, consider a case where the ZnO substrate 12 has n-type conductivity.

Specifically, an electrode pattern is formed by photolithography, electrode metal is deposited by resistance heating, EB (electron beam) or sputtering, and then sintered (sintered) to obtain, for example, Ti / Al or Ti A / Pt / Au electrode is formed as the n-type lower electrode layer 11. In this case, the formed n-type lower electrode layer 11 is in ohmic contact with the ZnO substrate 12.
In addition, before forming the lower electrode layer 11, it is preferable to thin the ZnO substrate 12 by CMP (mechanical chemical polishing).

  (Step 13) Next, a resonator end face of the semiconductor laser diode is formed. The resonator end face is formed by cleavage. Here, the cleavage plane is an m-plane.

(Step 14) Next, a low reflection film and a high reflection film are formed on the light emission side end face and the light reflection side end face of the formed resonator end face, respectively.
Thereby, the manufacture of the semiconductor laser diode 10 that emits light in the visible region of a long wavelength such as the green region is completed. According to 1st Embodiment comprised as mentioned above, there exist the following effects.

  ○ Since the pseudo lattice matching layer 13 is formed between the ZnO substrate 12 and the active layer 15, a steep nitride / oxide interface between the ZnO substrate 12 and the active layer 15 is obtained, and the activity of InGaN is achieved. Good crystals of layer 15 are obtained. As a result, it is possible to obtain a semiconductor laser diode as a highly reliable semiconductor light emitting element with high luminous efficiency.

  FIG. 4 shows the relative value of the PL half-value width when there is no pseudo lattice matching layer 13 as in the present embodiment. In FIG. 4, (A) to (E) indicate the PL half-value widths when the In composition is 0.24, 0.31, 0.37, 0.3, and 0.325, respectively.

  From FIG. 4, by forming the pseudo-lattice matching layer 13 between the ZnO substrate 12 and the active layer 15, the half-value width is narrower than when there is no pseudo-lattice matching layer, and the emission characteristics are good (the emission intensity is strong). ) A semiconductor laser diode can be obtained.

  ○ By configuring the pseudo-lattice matching layer 13 with GaN having a film thickness of 1 ML or more and a critical film thickness or less with respect to the substrate, while maintaining the lattice constant of the underlying ZnO substrate 12, By growing an active layer made of lattice-matched InGaN, an active layer having good crystals can be obtained.

  ○ By using the ZnO substrate 12, the InGaN active layer 15 having a high In composition ratio required for realizing a semiconductor laser diode (light emitting element in the green region) that emits light in a long wavelength visible region such as the green region is used. However, the influence and phase separation by the piezoelectric field can be suppressed. Therefore, it is possible to realize a conductor laser diode capable of obtaining long-wavelength green light emission with a high In composition InGaN system having a uniform composition distribution.

  Since the ZnO substrate 12 has n-type conductivity, the semiconductor laser diode 10 of the vertical device can be configured by forming the lower electrode layer 11 on the back surface thereof. That is, a current can flow from the front surface side to the back surface side of the ZnO substrate 12, and the semiconductor laser diode 10 of a vertical device (vertical injection device) can be realized.

  In the active layer 15 made of InGaN, the composition ratio of indium (In) is set so that the emission wavelength is 480 nm or more. Specifically, the active layer 15 is composed of an InGaN layer having an In composition (In composition ratio of about 30%) having a light emission wavelength in the green region, so that visible light having a longer wavelength than blue (for example, The semiconductor laser diode 10 capable of emitting (green) light can be realized.

  O Since the light guide layer 21 is formed between the lower clad layer 14 and the active layer 15 and the light guide layer 22 is formed between the active layer 15 and the upper clad layer 16, these light guide layers 21 and 22 are formed. Thus, light can be stably and efficiently confined in the central active layer 15 functioning as a core.

  The above epitaxial wafer for a semiconductor laser diode is formed on the c-plane (000_1) ZnO substrate 12 having an oxygen (O) polarity using the RFMBE method. Then, in the above (Step 1a), the surface flattening process, that is, the CMP (mechanical chemical polishing) process of the ZnO substrate 12 is performed, and then the oxygen (O) polar c-plane (000_1) ZnO substrate 12 is oxidized. By performing heat treatment in the atmosphere sandwiched between flat plates of an inorganic material such as zinc, a clean surface with good flatness is obtained on the oxygen (O) polar c-plane (see FIG. 2). FIG. 2 shows the CMP process when the epitaxial wafer is formed on an oxygen (O) polar c-plane (000_1) ZnO substrate 12 and a zinc (Zn) polar c-plane (000_1) ZnO substrate. The surface roughness after RMS (RMS) and the surface roughness after heat treatment (RMS) are shown. In FIG. 2, (A) shows the surface roughness after CMP treatment (chemical mechanical polishing) on a c-plane (000_1) ZnO substrate having a zinc (Zn) polarity. FIG. 5B shows the surface roughness after heat treatment of the zinc (Zn) polar c-plane (000_1) ZnO substrate. FIG. 5C shows the surface roughness after the CMP treatment on the c-plane (000_1) ZnO substrate 12 having an oxygen (O) polarity. FIG. 4D shows the surface roughness after heat treatment on the c-plane (000_1) ZnO substrate 12 having an oxygen (O) polarity.

  As shown in FIG. 2, when the epitaxial wafer is formed on the c-plane (000_1) ZnO substrate 12 having the oxygen (O) polarity, the surface flattening process (step 1a) is performed to obtain the oxygen (O) polarity. It can be seen that a clean surface with good flatness is obtained on the c-plane. As described above, since the surface of the ZnO substrate 12 becomes a clean surface with good flatness, the diffusion of Ga in the active layer 15 into the ZnO substrate 12 is further suppressed, so that the space between the ZnO substrate 12 and the active layer 15 is reduced. The steep interface is obtained, and a better crystal of the active layer 15 made of InGaN is obtained. As a result, the semiconductor laser diode 10 having high emission efficiency and high reliability can be obtained.

(Second Embodiment)
A semiconductor laser diode 10A as a semiconductor light emitting device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a schematic configuration of a semiconductor laser diode 10A according to the second embodiment.

  In the semiconductor laser diode 10 according to the first embodiment shown in FIG. 1, an epitaxial wafer for a semiconductor laser diode that emits light in a long-wavelength visible region such as a green region is obtained by the above (Step 1) to (Step 8). It is formed on the c-plane (000_1) ZnO substrate 12 having an oxygen (O) polarity by using the RFMBE method.

  On the other hand, in the semiconductor laser diode 10A according to the second embodiment, an epitaxial wafer for a semiconductor laser diode that emits light in a long-wavelength visible region such as a green region is formed on an m-plane (10_10) ZnO substrate using the RFMBE method. 12 is formed.

  The epitaxial wafer of the semiconductor laser diode 10A includes a buffer layer 23 made of ZnO formed on the ZnO substrate 12 and a pseudo lattice matching layer 13A made of a superlattice formed on the buffer layer 23. It is. The pseudolattice matching layer 13 </ b> A made of a superlattice is formed by growing a GaN crystal having a film thickness of 4 ML on the buffer layer 23. Other configurations of the epitaxial wafer of the semiconductor laser diode 10A are the same as those in the first embodiment.

  Next, a method for manufacturing the semiconductor laser diode 10A will be described focusing on differences from the manufacturing method described in the first embodiment.

  In the present embodiment, the above-described epitaxial wafer for a semiconductor laser diode that emits light in a long-wavelength visible region such as a green region is formed on the m-plane (10_10) ZnO substrate 12 using the RFMBE method by the following steps. To do.

  First, after performing the above (Step 1) (including (Step 1a) to (Step 1c)), in the next (Step 20), the buffer layer (ZnO buffer layer) 23 made of ZnO is formed on the m-plane (10_10). It is formed on the ZnO substrate 12.

  (Step 20) After growing the ZnO buffer layer 23 of about 100 nm at a growth temperature lower than 750 ° C., after heat treatment at 1000 ° C., the ZnO buffer layer 23 of about 1000 nm is deposited at 800 ° C. Thereby, a high quality ZnO buffer layer 23 can be grown. At this time, the ZnO buffer layer 23 is made n-type conductive by doping at least one of Al, Ga, and In with the ZnO buffer layer 23.

Next, instead of the above (Step 2), the following (Step 21) is performed.
(Step 21) By simultaneously supplying Ga and nitrogen radicals (N) to the substrate surface at a temperature lower than 750 ° C., for example, a low temperature of about 500 ° C., a GaN crystal is grown on the ZnO buffer layer 23 to have a film thickness of 4 ML. A pseudo lattice matching layer 13A made of 4ML GaN crystal is formed.

  Here, by doping silicon (Si), the pseudo lattice matching layer 13A can be made to be n-type conductive. The reason why the growth temperature is low is to suppress the interfacial reaction between the ZnO substrate and GaN.

  In the present embodiment, when the lower cladding layer 14 is formed in the above (Step 3), the growth temperature is set to a temperature lower than 750 ° C., for example, 450 ° C., and the raw material is set to a desired cell temperature. AlGaInN crystal is grown by supplying some In, Ga and Al together with N onto the ZnO substrate 12. At this time, the composition of AlGaInN is lattice-matched with ZnO, but since it is grown on the m-plane substrate 12, both the a-axis and c-axis lattice constants cannot be matched. Therefore, (a) adjust the composition to lattice match in the a-axis direction, (b) adjust the composition to lattice match in the c-axis direction, (c) between the lattice matching composition of the a and c-axis Here, the three lattice adjustment conditions for adjusting the composition are called lattice matching of nitride semiconductor growth on the m-plane ZnO substrate, and the lattice constants are matched.

  When forming the light guide layer 21 in (Step 4), an InGaN crystal is grown by supplying In in addition to Ga and N while keeping the growth temperature lower than 750 ° C., for example, 450 ° C. At this time, the In composition of the InGaN layer is set between the composition of the lower cladding layer 14 and the active layer 15.

  (Step 5) Next, change the cell temperature setting so that the growth temperature remains lower than 750 ° C., for example, 450 ° C., so that the optimal In / Ga ratio and V / III ratio are obtained (or a plurality of If you have a cell, switch to the preset In and Ga cells), and supply it to the substrate with N, so that the In composition (about 30%) with the emission wavelength in the green region An active layer 15 made of InGaN is formed.

  Further, when the light guide layer 22 is formed in the above (Step 6), an InGaN crystal is grown by supplying In in addition to Ga and N while keeping the growth temperature lower than 750 ° C., for example, 450 ° C. . At this time, the In composition of the InGaN layer is set between the composition of the lower cladding layer 14 and the active layer 15.

  Other steps for producing the epitaxial wafer are the same as those in the first embodiment.

  Further, when the upper cladding layer 16 is formed in the above (Step 7), In, Ga, and Al, which are raw materials set at a desired cell temperature with the growth temperature lower than 750 ° C., for example, 450 ° C., are changed to N. Then, an AlGaInN crystal is grown by supplying the ZnO substrate 12 together. At this time, the composition of AlGaInN is lattice-matched with ZnO, but since it is grown on the m-plane substrate 12, both the a-axis and c-axis lattice constants cannot be matched. Therefore, (a) adjust the composition to lattice match in the a-axis direction, (b) adjust the composition to lattice match in the c-axis direction, (c) between the lattice matching composition of the a and c-axis Here, the three lattice adjustment conditions for adjusting the composition are called lattice matching of nitride semiconductor growth on the m-plane ZnO substrate, and the lattice constants are matched.

  Through the above steps, an epitaxial wafer for the semiconductor laser diode 10A that emits light in the visible region of a long wavelength such as a green region is manufactured. Thereafter, by using the manufactured epitaxial wafer, a laser diode structure is manufactured by (Step 9) to (Step 14) described in the first embodiment, so that light is emitted in a long-wavelength visible region such as a green region. The manufacturing of the semiconductor laser diode 10A is completed. According to 2nd Embodiment comprised as mentioned above, in addition to the effect which the said 1st Embodiment show | plays, there exist the following effects.

  ○ By forming a buffer layer 23 made of ZnO between the ZnO substrate 12 and the active layer 15, a buffer layer surface having good flatness can be formed, so that an active layer made of InGaN lattice-matched with the ZnO substrate 12 is formed on the buffer layer 23. By growing 15, an active layer 15 made of InGaN having better crystals can be obtained. As a result, a semiconductor laser diode with further improved luminous efficiency and reliability can be obtained.

In addition, this invention can also be changed and embodied as follows.
In each of the above embodiments, the present invention can also be applied to a semiconductor light emitting device such as a semiconductor laser diode having no light guide layers 21 and 22. That is, the present invention is a semiconductor light emitting device comprising a ZnO single crystal substrate and a pseudo lattice matching layer, a lower clad layer, an active layer, an upper clad layer, and a contact layer sequentially formed on the ZnO single crystal substrate. It can be widely applied to semiconductor laser diodes.

  In addition, the present invention uses a ZnO single crystal substrate, a substrate surface treatment step for modifying the surface thereof, and a lower clad layer formation for forming a lower clad layer lattice-matched to at least one of the ZnO single crystal substrate or the active layer A step of forming an active layer made of gallium indium nitride [InxGa1-xN (0 <x <1)] on the lower clad layer, and a pseudo between the ZnO single crystal substrate and the active layer. A pseudo-lattice matching layer forming step for forming a lattice matching layer; an upper clad layer forming step for forming an upper clad layer lattice-matched to at least one of the ZnO single crystal substrate or the active layer on the active layer; and the upper clad layer. The present invention can be widely applied to a method for manufacturing a semiconductor light emitting device such as a semiconductor laser diode provided with a contact formation step for forming a contact layer thereon.

  In each of the above embodiments, the ZnO substrate 12, the pseudo lattice matching layer 13, the lower cladding layer 14, the light guide layer 21, and the lower electrode layer 11 are each provided with p-type conductivity, and the light guide layer 22 and the upper cladding layer 16. The present invention can also be applied to a semiconductor laser diode as a semiconductor light emitting device in which the contact layer 17 has n-type conductivity.

  In the first embodiment, the epitaxial wafer for the semiconductor laser diode is formed on the c-plane (000_1) ZnO substrate 12 having an oxygen (O) polarity by using the RFMBE method. The present invention is also applicable to a semiconductor light emitting device such as a semiconductor laser diode formed on a (Zn) polar c-plane (000_1) ZnO substrate 12. In this case, as shown in FIG. 2, the flatness is somewhat rougher than that of the c-plane (000_1) ZnO substrate having an oxygen (O) polarity. As a result, a clean surface with good flatness can be obtained on the c-plane of zinc (Zn) polarity. As a result, the diffusion of Ga in the active layer 15 into the ZnO substrate 12 is suppressed, so that a steep interface between the ZnO substrate 12 and the active layer 15 is obtained, and an even better crystal of the active layer 15 made of InGaN. Is obtained. As a result, a semiconductor light emitting device such as a semiconductor laser diode having high emission efficiency and high reliability can be obtained.

  In the first embodiment, the pseudo lattice matching layer 13 is a layer in which a GaN binary material is grown at the initial stage of growth on the ZnO substrate 12 and the In composition is gradually increased on the GaN layer (InGaN gradient). A pseudo lattice matching layer in which a composition layer) is formed may be used. In this configuration, a GaN binary material is grown in the early stage of the growth of the pseudo lattice matching layer 13 to obtain a sharp interface between ZnO and a nitride semiconductor (an active layer made of InGaN).

  In the second embodiment, in order to form the pseudo lattice matching layer 13A, 4ML InN may be grown instead of 4ML GaN. Alternatively, the pseudo lattice matching layer 13A made of a superlattice may be formed of a layer in which GaN and InN having a thickness of 1 ML or more and a critical thickness or less with respect to the substrate are stacked. For example, the pseudo-lattice matching layer 13A may be configured by a layer in which 4ML GaN and 1ML InN are alternately stacked, or a layer in which 1ML GaN and 4ML InN are alternately stacked. In the case of the pseudo-lattice matching layer 13A composed of a superlattice having such a laminated structure, the critical film thickness of the pseudo-lattice matching layer 13A is defined by the critical film thickness corresponding to InGaN when the average composition of GaN and InN is taken. The

  In any case of such a configuration, the pseudo-lattice matching layer 13A made of a superlattice has a film thickness of 1 ML or more and a critical film thickness or less with respect to the substrate. By growing the active layer 15 made of InGaN lattice-matched with the ZnO substrate 12 while maintaining the lattice constant, the active layer 15 having a good crystal can be obtained. As a result, a semiconductor light emitting device such as a semiconductor laser diode having high emission efficiency and high reliability can be obtained.

  In the first embodiment, the epitaxial wafer is formed on the c-plane (000_1) ZnO substrate 12 having an oxygen (O) polarity, but the plane orientation of the ZnO substrate 12 is slightly inclined from the c-plane (000_1). A surface with an off angle of 1 ° or less in the a-axis direction or a slightly inclined surface (an off angle of 1 ° or less in the m-axis direction) may be used.

  In the second embodiment, the plane orientation of the ZnO substrate 12 may be a plane equivalent to the (1_100) plane (m plane).

  In each of the above embodiments, the plane orientation of the ZnO substrate 12 is changed to the (11_20) plane (a plane), the plane equivalent to the a plane, the (11_22) plane, the plane equivalent to the (11_22) plane, or ( It may be a plane equivalent to the 10_1_1) plane or the (10_1_1) plane.

  In each of the above embodiments, the semiconductor light emitting element configured as a semiconductor laser diode has been described. However, the present invention can also be applied to a semiconductor light emitting element such as a light emitting diode (LED) having a pn junction.

  In each of the above embodiments, the active layer 15 is made of InGaN, but the present invention can also be applied to a semiconductor light emitting device in which the active layer 15 is made of another group III-V nitride compound semiconductor such as AlGaInN. It is.

  In each of the above embodiments, the present invention can be applied to a configuration in which the active layer 15 has a quantum well structure.

  In each of the above embodiments, even when the active layer 15 made of InGaN is made of AlGaInN, the lattice constant of the ZnO substrate 12 is close to AlGaInN (lattice matching) like InGaN. Even if the composition is increased, phase separation is suppressed. As a result, an AlGaInN active layer having a uniform In composition can be obtained even if the In composition is increased, so that light is emitted in the visible light region from blue to red, particularly visible light having a longer wavelength than blue (eg, green). A semiconductor light emitting device can be realized.

Sectional drawing which shows schematic structure of the semiconductor laser diode which concerns on 1st Embodiment. Surface roughness (RMS) after CMP and surface roughness (RMS) on c-plane (000_1) ZnO substrate with oxygen (O) polarity and c-plane (000_1) ZnO substrate with zinc (Zn) polarity Graph showing. A graph for explaining a critical film thickness. The graph which respectively shows the numerical value of PL half value width in the case where there is no pseudo lattice matching layer and when it exists. Sectional drawing which shows schematic structure of the semiconductor laser diode which concerns on 2nd Embodiment. (A) is explanatory drawing which shows a mode that Ga was diffused in a ZnO single-crystal substrate, (B) is a photograph which shows the mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10A ... Semiconductor laser diode as semiconductor light emitting element, 11 ... Lower electrode layer, 12 ... ZnO single crystal substrate, 13, 13A ... Pseudo lattice matching layer, 14 ... Lower clad layer, 15 ... Active layer, 16 ... Upper clad Layer, 17 ... contact layer, 18 ... passivation film, 19 ... upper electrode layer, 21, 22 ... light guide layer, 23 ... buffer layer.

Claims (16)

A ZnO single crystal substrate,
An active layer made of gallium indium nitride [In x Ga 1-x N (0 <x <1)];
A pseudo lattice matching layer formed between the ZnO single crystal substrate and the active layer;
An upper cladding layer and a lower cladding layer lattice-matched to at least one of the active layer or the ZnO single crystal substrate;
And a contact layer formed on the upper cladding layer.   2. The semiconductor light emitting element according to claim 1, wherein the pseudo lattice matching layer is made of GaN having a thickness of 1 ML or more and a critical thickness or less with respect to the substrate.   The semiconductor light emitting device according to claim 1, wherein the pseudo lattice matching layer is made of a super lattice.   2. The semiconductor light emitting element according to claim 1, wherein the pseudo lattice matching layer made of a superlattice is a super lattice layer made of GaN and InN having a thickness of 1 ML or more and a critical thickness or less with respect to the substrate. .   The lower cladding layer is made of zinc magnesium beryllium cadmium [Zn 1-abc Mg aBeb CdcO (0 ≦ a <1, 0 ≦ b <1, 0 ≦ c <1, a + b + c ≦ 1)]. The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting device is a light-emitting device.   The semiconductor light-emitting element according to claim 1, wherein the lower cladding layer is zinc oxide.   5. The lower cladding layer according to claim 1, wherein the lower cladding layer is made of aluminum gallium indium nitride [Al 1 -pq Ga p In q N (0 ≦ p <1, 0 ≦ q <1, p + q ≦ 1)]. The semiconductor light emitting element of any one of Claims.   8. The composition ratio of indium (In) in the active layer is set so that an emission wavelength is 480 nm or more and 650 nm or less. 8. Semiconductor light emitting device.   9. The semiconductor light emitting device according to claim 8, wherein a composition ratio of the indium (In) is 20% or more and 60% or less.   10. The semiconductor light emitting device according to claim 1, further comprising a light guide layer between the active layer and the clad layer. 11.   11. The semiconductor light-emitting element according to claim 1, wherein a buffer layer made of ZnO is formed between the ZnO single crystal substrate and the active layer.   Using a ZnO single crystal substrate, a substrate surface treatment step for modifying the surface of the ZnO single crystal substrate, and forming a lower clad layer for forming a lower clad layer lattice-matched to at least one of the ZnO single crystal substrate or the active layer An active layer forming step of forming an active layer made of gallium indium nitride [Inx Ga1-xN (0 <x <1)] on the lower clad layer, and the ZnO single crystal substrate and the active layer A pseudo-lattice matching layer forming step for forming a pseudo-lattice matching layer therebetween, and an upper clad layer forming step for forming an upper clad layer lattice-matched to at least one of the ZnO single crystal substrate or the active layer on the active layer And a contact layer forming step of forming a contact layer on the upper clad layer.   13. The semiconductor according to claim 12, wherein the pseudo lattice matching layer forming step forms the pseudo lattice matching layer with a GaN layer having a film thickness of 1 ML or more and a critical film thickness or less with respect to a ZnO substrate. Manufacturing method of light emitting element.   13. The method of manufacturing a semiconductor light emitting device according to claim 12, wherein the pseudo lattice matching layer forming step uses nitrogen plasma and grows at a low temperature.   13. The semiconductor light emitting device manufacturing method according to claim 12, wherein in the pseudo lattice matching layer forming step, heat treatment is performed in vacuum, oxygen atmosphere or oxygen plasma irradiation before forming the pseudo lattice matching layer. Method. 16. The semiconductor light emitting device according to claim 12, wherein the pseudo lattice matching layer is formed on an oxygen (O) polar c-plane (000_1) of the ZnO single crystal substrate. .

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