Semiconductor light emitting element and manufacture thereof

[Detailed Description of the Invention]

[Industrial Application] The present invention relates to the semiconductor light emitting element for providing visible region luminescence, especially relates to a light emitting diode, thin film electroluminescent elements, and those manufacturing methods. [Description of the Prior Art] The light emitting diode using the conventional ZnS had obtained blue luminescence from the thin film type MIS structure which laminated successively the ZnS layer, high resistance layer, and electrode layer which added impurities, and constituted them on the semiconductor substrate. JP,61-164275,A, a said 61-1723n+ item gazette, etc. are mentioned as prior art relevant to this kind of semiconductor light emitting element. The impurities additive-free ZnS layer was used as the low resistance n-ZnS layer in which the semiconductor light emitting element of these former added Am as an impurities addition ZnS layer, and a high resistance layer. In JP,61-240592,A, using for thin film electroluminescence the ZnS layer which added one sort in Au, Ag, and Cu as 7 Cusceptor with the halogen donor as a luminous layer is proposed. [Problem(s) to be Solved by the Invention] About a light emitting diode, there was a problem that luminous efficiency's being low and the stability of an emission spectrum were bad among the conventional technologies mentioned above. Blue luminescence from this light emitting diode originates in the luminescence center of Acceptor which arises according to a crystal defect with AQ donor. That is, trivalent A party ion forms the donor level of ~150meV in a ZnS crystal. And the hole of Zn forms a deep acceptor level (~700me V). Thus, there was a problem that it was very difficult to control the concentration of Acceptor which occurs spontaneously with sufficient reproducibility. Between An donor and Vzn Acceptor, since two luminescence belts by the self activation (SA) compound center and a donor Acceptor (DA) center arose, there was a problem in the stability of an emission spectrum. There was a problem that rate-limiting [ of the luminous efficiency ] was carried out to the low hole pouring rate from a high resistance layer. And about thin film electroluminescence, in order to dope Acceptor by thermal diffusion, there was a problem that the stability and luminous efficiency based on DA which were formed were bad among the above-mentioned conventional technologies. The object of the present invention cancels the problem of the above-mentioned conventional technology, and there is in providing a highly efficient blue light-emitting diode in which high luminous efficiency is shown, and a manufacturing method for the same. Other objects of the present invention are to provide a highly efficient light emitting diode which shows Full color according to high luminous efficiency, thin film electroluminescence, and a manufacturing method for the same. [Means for solving problem] In order to achieve the object of the above-mentioned present invention, the technical means applied to the semiconductor light emitting element of the 1 present invention are explained. It is possible to control by adding predetermined impurities during a ZnS crystal to 'n type or p type conduction generally. The conducted type and the relation of ionization energy at the time of adding various impurities are collectively shown in the 1st table. Following space 1st Table The molecular beam epitaxy (MBE) method, the organometal chemistry vapor-phase-epitaxy (MOCVD) method, and gas sauce MBE which are thermal nonequilibrium growth about formation of n type ZnS (MOMBE) law, ~1ohm and one or less semiconductor membrane crystal are easily obtained with the dope of the periodic table ■ fellows of an element, or ■ fellows element. However, although p type conduction is obtained about p type ZnS with the dope of N which is Li, Na, or ■ fellows element which is a periodic table [ of an element ] I fellows element, it is difficult to obtain the low resistance below 1ohm and G. Even if the above-mentioned pn control forms pn junction using easy ionic species, only luminescence purple outside beyond photon energy 3eV can be obtained. However, it is forming donor Acceptor pair into ZnS combining Cu or Ag which is not so suitable as p type impurities, and suitable donor impurities, and it is possible to obtain luminescence of blue~red. This coactivation ZnS serves as high resistance, in order that Acceptor may compensate an electric charge mutually with a donor, but it can lower resistance slightly by changing into the state of fault compensation of other electric charges with one of ion. Then, in the present invention, in order to obtain the semiconductor light emitting element which provides efficient visible region luminescence, the active layer which presents luminescence of donor Acceptor pair was applied to the semiconductor light emitting element. An example of the structure of the semiconductor light emitting element by the 1 present invention is shown in Drawing 1. it is shown in a figure -- as . n which the semiconductor light emitting element of the present invention formed two in five layers of n"-Zn(s) of low resistance on semiconductor substrate 1, then doped donor Acceptor pair Eight layers three of Zn(s) and three layers of pf-Zn form 4, and, finally it forms lower electrode 5a and top electrode 5b. In this ntnp↑ structure, it is one feature of the present invention to have formed [ three ] donor Acceptor pair in eight layers of n-Zn. The n"np Tanker structural energy semi- grade in the semiconductor light emitting element of the present invention is shown in Drawing 2. In a figure, it is Eg (being room temperature ~ 3.6 eV) about the energy gap of ZnS, a Fermi level -- EF and a conducting zone -- the acceptor level in Eo and eight layers of pf-Zn4 is shown for the donor level in V, B, and eight layers of nt-Zn2, and C, B, the valence band, the donor level in EA0 and eight layers of n-Zn3, and Eo2 and an acceptor level are shown as EA2. the feature of the energy level according to the present invention here -- Eo, <=ED2, and EA1<= -- it EA(s) and comes out and is a certain thing. The semiconductor light emitting element which shows the ionic species which fill the relation of such an energy level in Drawing 1 with five layers two of nt-Zn and three layers of eight layers of n-Zn3.2 Samurai-Zn(s) doping to 4, respectively is obtained. S mix crystal is applicable similarly as a crystal material (Zn, Cd). In order to realize structure of the semiconductor light emitting element by the present invention, the method for film deposition by the chemicals vapor phase growth (CVD method) which is a method of growing up under thermal nonequilibrium, the decompression MOCVD method especially the pressure at the time of a reaction is 100 or less Torr, or the gas sauce MBE method was adopted. AQ and CQ, next, the ionic species used in order to obtain blue, green, and a red light emitting diode are I, Ag, Cu, N, and Li. In order to realize full color-ization of thin film electroluminescence, ZnxCdl-xs containing donor Acceptor pair formed by the thermal nonequilibrium growing-up method was adopted as a luminous layer of thin film electroluminescence. [For Work ] Luminescence obtained from pn junction diode using n in which low-resistance-izing of ZnS is possible, and p type impurities is restricted to a near ultraviolet region. Donor Acceptor coactivation Zn5N adopted in the present invention works as a recombination region of the electron poured in from a n-ZnS layer, and the electron hole poured in from a p-ZnS layer. By it, DA (donor Acceptor) pair under coactivation ZnS serves as a re-joint center, and generates the photon of the energy equivalent to the energy difference between DA pairs. Here, in ZnS, Ag-cn and Ag-AQ which are DA pairs commit a blue center, Cu-CQ, and Cu-AQ as a green center. Since Cu-CQ and Cu-AQ in S (Zn, Cd) work as a red center, they can obtain a trichromatic light emitting diode. And the MOCVD method and the gas sauce MBE method which were adopted as the technique of forming a ZnS film or (Zn, Cd) S film, Since the compound semiconductor film which doped impurities can be stabilized and grown up under thermal nonequilibrium, it is quality and can form coactivation ZnS or (Zn, Cd) S film with high luminous efficiency. In order that thin film electroluminescence may form a ZnS luminous layer on an oxide, a ZnS film turns into a multi-crystal film. As for a donor and Acceptor, generally, about 50~100 persons' Distance of change, with pA pair center are formed. Therefore, a possibility that a crystal defect exists that the crystal child who is the minimum size of many crystallines is the size below 50~100A between DA pair centers increases, and it is thought that luminous efficiency falls. It is thought that the ZnS film formed by decompression MOCVD can perform formation of an efficient donor Acceptor coactivation layer since it has big crystal child size. Since the coactivation ZnxCdl-xs film formed with the CVD method also as that of suitable growth pressure has A pair in big crystal child size and stability, it is applicable also to the thin film electroluminescent element which impresses a high electric field. [Example] Hereinafter, one example of the present invention is given and it explains in detail based on one drawing. (Example 1) The structure of the semiconductor light emitting element produced in this example is shown in Drawing 3. n-GaAs board 6 of low resistance was used for the semiconductor substrate. First, n A ZnS:AQ layer 7 was formed in 4-micrometer film thickness as an n+-ZnS layer. Next, as an n -ZnS layer, it is n-ZnS. : Ag and AQ layer 8 were formed in 1 micrometer of film thickness. And as for 4pm, film thickness t This formation carried out p'-ZnS:N layer 9 as a pt-ZnS layer. H which is finally a semiconductor substrate about InGa alloy electrode 10 and Au electrode 11, respectively It formed on the reverse side of GaAs board 6, and pf-ZnS:N layer 9, and used heat treatment for considering it as ohmic nature as the deed ohmic-for 5 minutes electrode by 380 degreeC. In n 1"n 9 in this example, formation of structure grew up nfn and p? each class continuously, using the decompression MOCVD method (organometal chemistry vapor phase growth) as a epitaxially growing method. DEZn (diethylzinc) and HXS (the thing of 2% of hydrogen dilution is used hydrogen sulfide and here) were used as materials of Zn and S. As doping materials, they are TEAQ (triethyl aluminum), C, and H. AlhPz (Bis mum Dimethylmethylene phosphorus nil methyldi silver), NH, and (ammonia gas) were used. After, as for growth of each ZnS film, below I X 10-'Torr carried out back pressure, it performed 350degreeC and growth pressure for substrate temperature as ITorr. rl-GaAs board 6 -- H, S04:H, and O: H and 0 (7) -- after carrying out surface washing using etchant of mixture ratio 4:1= 1, ++n10-ZnS which heat-treated 550 degreeC for 10 minutes in the reactor : The materials flow at the time of formation of 7 of one layer of Af(s) is 30 cc/min, H, and S/H2 about DEZn 900 cc/Iain T E A Q /H was made into 10 cc/min. TEAQ was introduced into the reactor by making H2 into carrier gas. The materials cylinder temperature of DEZn made 15 cc/win 10 cc/win and Ag Acceptor materials flow for AQ donor materials flow in formation of n-ZnS:Ag and AQ layer 8 zero-order [ which was set to 15 degreeC ]. AQ and the charge Sylph cylinder of AgJW at this time were respectively held to -5~0 degreeC and 60~90 degreeC. p10-ZnS:N layer 9 used NH for nitrogen materials, and 100 cc of the flow set it to /win. DEZn at this time and the flow of Hz S /H, were taken as 400 cc/win and 700cc / ll1inch, respectively. Direct-current current was impressed between Au electrode 11 of the semiconductor light emitting element formed by the above-mentioned technique, and the electrode of InGa alloy electrode lO. As a result, blue luminescence which has an emission spectrum as shown in Drawing 4 by more than impressed-electromotive-force 10V was obtained. The broadcloth spectrum to which an emission spectrum has a peak near 460~470 nm was obtained. n-ZnS which formed this as a recombination region of an electron and an electron hole : It is thought that it is based on luminescence from Ag and AQ layer 8. As for AQ donor level, ~720meV and N acceptor level of ~100meV and Ag acceptor level were ~130meV. n type impurity level Eo2 and p type impurity level EA of 1 or 9 layers of n type impurity levels ED of n" layer of the semiconductor light emitting element of That and n↑np Structure which it had and was produced in this example, The energy relationship between p type impurity level EA1 of p" layer showed a relation called ED Yu =Eo and EAx>EAx. As a result, it is thought that good blue luminescence of color purity as shown in Drawing 4 was obtained. In this example, although DEZn was used as zinc materials, when Zn(CH:+) z (dimethyl zinc) was used, even if the temperature of the materials cylinder was near 0 degreeC, sufficient flow was obtained. And the blue light-emitting diode with the same good characteristic as this example was obtained. As a combination of the impurities which form DA pair, Ag-CQ, Au-AQ, Au-CQ, Cu-AQ, Cu-GQ, etc. can be applied, and they are Cu (C, H) and P (C, H) as AuCH, - (QCF), C, H, and Cu materials as Au materials. It is checking that formation of Using and the above-mentioned DA pair is possible with the manufacturing method of this example. The halogen element was able to apply iodine and bromine besides chlorine. (Example 2) An example of the structure of the semiconductor light emitting element produced in this example is shown in Drawing 5. n-GaP board 12 of low resistance is used for a semiconductor substrate, and it is on it, It is nl-ZnS as an n"-ZnS layer. : A Q 1113 is formed in a thickness of 3 micrometers, and then it is rI as a n-ZnS layer. ZnS : It is 2 Samurai-ZnS as a p To [ after growing up Cu and A 0 layer 14 into a thickness of 1 micrometer ]-ZnS layer. : N layer 15 was made to form in a thickness of 3 micrometers. Growth of each class performed growth pressure by decompression MOCVD set to 0.ITorr. Using DEZn, H, S, and TEAQ, Cu (C, H) and P (C, H)3 (cyclopentadienyl copper and Triethyllin) were used for the used materials as Cu materials, and NH was used for them as a charge of NI. Temperature of the materials cylinder was set to 60~70 degreeC, and transportation of the charge of Cui was performed by controlling H2 carrier-gas flow to 10~15 cc/win. - which performed membrane formation conditions other than the growth pressure of each class like Example 1 The six-shot light color which was the broadband [ luminescence / which was obtained from the semiconductor light emitting element produced in this example ] with a peak of 530na+ showed green with sufficient color purity. The electron poured in from n"-ZnS:AQ layer 13 this [ whose ] is n 9 layer, and p+-ZnS which is p middle layer : Electron hole poured in from N layer 15, n -ZnS of high resistance which is a recombination region : It is shut up into Cu and A zero-layer 14, and a radiation reassociation process is taken between AQ donor's semi- grade, and the semi- grade of Cu Accept evening. As a result, it is thought that good green luminescence with about 2.3 eV of photon energies is obtained. (Example 3) An example of the structure of the semiconductor light emitting element produced in this example is shown in Drawing 6. On each class of p t n n+ structure using n-Cd5 substrate 18 of low resistance as a semiconductor substrate, p A Zn, Cd0., S : N layer 21, n Zno, 5 Cdo-zS : Cu, AQ layer 20, and gray Dito n"-ZnxCd Knee Huh S to which the mix-crystal ratio was changed from 0 to 0.8: 19 [ ten-layer ] was made to form, respectively. DEZn, H2S, and DMCd (Dimethyl cadmium) were used for materials, and growth of the ZnxCdl-xS thin film was performed by the decompression MOCVD method. The mix crystal ratio was controlled by materials flow rate of DEZn and DMCd. Setting temperature of the materials cylinder of DMCd to 0 degreeC, and changing a flow from 40 to 10 cc/win, the flow of DEZn was also changed from O with 40 cc / +++in, and was grown up. The film thickness of the gray Dito layer was 5 micrometers. Good red [ semiconductor light emitting element / which was produced in this example ] luminescence with a peak of wavelength 630 r+n+ was obtained. (Example 4) It asked for the relation with the luminescence intensity of a semiconductor light emitting element, growth pressure, and growth temperature which were formed by the technique of Example 1 in this example. Drawing 7 shows the relation between luminescence intensity (relative value), growth pressure (Torr), and a growth rate (micrometer / h). The materials ratio of the element of the periodic table ■ fellows / ■ fellows of an element was made as fixed as 1.5-, the flow of Hz s /H2 and DEZn was changed, and growth pressure was adjusted. luminescence intensity shows the maximum intensity in a field with a growth pressure [ Torr ] of 10-S~10 degrees -- 10" -- the pressure below Torr also showed 80% of luminescence intensity of the maximum. However, when growth pressure was made extremely low, for example, below 10-'Torr carried out, below in /h, 0.5 micrometer of growth rates became, and were not practical. Therefore, as for growth pressure, it is preferred to use the range of 10-4~101Torr. The relation between growth temperature (degreeC) and luminescence intensity (relative value) is shown in Drawing 8. As for growth temperature, although comparatively strong luminescence intensity is obtained more than 200 degreeC, it is more preferred to use more than 300 degreeC. Therefore, membrane formation by the CVD method which set growth pressure to 100 or less Torr, and made growth temperature more than 200 degreeC is appropriate as manufacturing conditions of the semiconductor light emitting element of the present invention. When making donor Acceptor coactivation ZnxCd and xsi form with the manufacturing method of Example 1 on the substrate which has a glass substrate top or an insulating film, It is desirable for below 600 degreeC to carry out growth temperature, and to make growth pressure more than 10'''4Torr, and it can use effectively not only hydrogen but a helium or nitrogen as carrier gas. [Effect of the Invention] As explained to details above, according to a semiconductor light emitting element of the present invention, and a manufacturing method for the same, no matter it may be what semiconductor device with the band gap more than the energy corresponding to a visible region, it is applicable as an efficient light emitting element which has visible luminescence. Since especially ZnxCdl-xs system material is applicable, the former carries out MIS type luminescence Light emitting diode comparison, and luminous efficiency high single or more figures is acquired. A n"np+ joining layer which constitutes a semiconductor light emitting element of the present invention can be easily formed with a CVD method, and is excellent also in mass production nature. As for a life of an element, a semiconductor light emitting element with 10,000 hours or more and high reliability is obtained. Since a quality film can form n+np of the semiconductor device of the present invention easily also on the substrate in which a joining layer has a glass substrate top or an insulating film, it becomes realizable [ the thin film fluorescence object for efficient thin film electro LUMINEC, a sense element, or projected type cathode-ray tubes ].

[Brief Description of the Drawings]

Drawings 2 are a mimetic diagram in which Drawing 1 shows an example of the structure of the semiconductor light emitting element of the present invention, and an explanatory view showing the energy level in the semiconductor light emitting element shown in Drawing 1, Drawing 3 is a mimetic diagram showing an example of the structure of the semiconductor light emitting element produced in Example 1 of the present invention, The graph which shows the emission spectrum of the semiconductor light emitting element which showed Drawing 4 in Drawing 3, Drawing 5 is a mimetic diagram showing an example of the structure of the semiconductor light emitting element produced in Example 2, The mimetic diagram showing an example of the structure of the semiconductor light emitting element which produced Drawing 6 in Example 3, the graph Drawing 7 indicates the relation between the growth pressure of the semiconductor film of the present invention, luminescence intensity, and a growth rate to be, and Drawing 8 are graphs which show the relation between the growth temperature of the semiconductor film of the present invention, and luminescence intensity. 1 ... Semiconductor substrate 2 ... Eight layers of nt-Zn3- n -ZnS layer 4 and "Pt-Zn8 layer 5a [ ... n-GaAs board / 7- n A ZnS:An layer B---n-ZnS : Ag, ] ... Lower electrode 5b ... Top electrode 6 Afi layer 9-pf-ZnS : N layer 10=InGa alloy electrode 11=Au electrode 12-n-GaP board 13- nt -ZnS : A zero-layer 14- n -ZnS : Cu, A Q layer 15"'P"ZnS : N layer 16 ... Lower electrode 17 ... Top electrode 18 ... n-Cd5 substrate 19 -.. Gray Dito n"-ZnxCdl-xS : A zero-layer 20- n -ZnolCdo, S : Cu, A zero-layer 21- pf-Zn, Cd, S : N layer 22 ... Lower electrode 23 ... The top electrode 3rd figure tabulation (nm) Drawing 4 (+-Z n S layer) n-ZnS layer - "-ZnS layer The 2nd