DE1489518A1 - Light-emitting diode and process for their manufacture - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT

U89518

Light-emitting diode and process for their manufacture

Luminescence diodes are semiconductor diodes with a pn junction, which when applied a voltage in the forward direction at the pn junction and undirected, incoherent electromagnetic in its immediate vicinity

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'Emit trahlunp in the infrared, visible or ultraviolet spectral association. AIo semiconductor material for these luminous diodes III-V compounds are particularly suitable. For example, luminescent diodes also emit gallium arsenide radiation in the infrared and T.urinec.enzrlioden now gallium phosphide radiation: in the visible Spectral range The wavelength of the emitted radiation depends on the width of the forbidden energy tones of the semiconductor. rials. The luminescence diodes are for optoelectronic applications suitable for the most spanking kind. Beiapieliaweiae know with their Help electrical 'signals are converted into light signal * and so on optieohem We, nj exceeded v / earth. for numerous applications, especially for the transmission of signals over longer distances, it is worthwhile that the light output of the luminescent diodes is possible large. However, the light output is limited by the current load capacity and the optiaohen properties of the Rajlbieitermateri & ls used for the diode.

In the case of the ordinary luminous diodes with semi-conductor bodies, large losses of lithium ink occur due to total reflection of the radiation emitted at the pn junction at the boundary surfaces of the conductive body. It is known that the losses caused by total reflection are largely avoided by hemispherical ice formation in one of the sons of the semiconductor body 3 of the luminescent diode. So that the light ejalttiarte pn junction is substantially perpendicular to the hemispherical surface to Meet t _t AWSS doing "the Durchiaea- he the radiant Fläohe of ρη-ttbergenga small compared to the radius of the hemisphere to be. Dta with the well-known Luaineszenzdioden the charge

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carrier concentration in the two., including the pn junction Zones of the semiconductor body and also in its hemispherical Part is relatively large, however, the emitted radiation is partially absorbed again within the light emitting diode. Since the Absorption losses increase with increasing thickness of the irradiated semiconductor material and therefore with increasing radius of the hemisphere The hemispherical radius is more and more important, since losses in light output are precisely avoided should. Because the diameter of the radiating surface of the pn junction must be small compared to the spherical radius, the limitation of the spherical radius also affects the radiating surface of the pn junction the end. Hemispherical radii of 1 mm and the corresponding diameter of the radiating surface of the pn junction of about 0.4mm. Since excessive heating of the light emitting diode must be avoided, the small area of the pn junction also means the current-carrying capacity of the diode and thus the achievable light output are limited.

The invention relates to a light emitting diode consisting essentially of one hemispherical semiconductor body containing a pn junction, the Ealbkugelradius greater than the diameter of the radiating The area of the pn junction is where the disadvantages mentioned do not occur and both reflection and absorption losses are largely avoided.

The light emitting diode is designed according to the invention so that in to one of the two semiconductor ions enclosing the pn junction adjacent, essentially hemispherical part of the half-conductor body the carrier concentration is smaller than in the

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two semiconductor zones enclosing the pn junction.

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By using semiconductor material with a lower carrier concentration for one of the two, the pn junction one semicircular adjoining semicircular semicircular-in part d * es semiconductor body are genäß the in the light emitting diode. invention more closely. the well-known luminescence diodes the absorptior? - it is greatly diminished, as the radiation is absorbed through it free Lqrciunps carrier is diminished. The radius of the Hnlbku. ^ El and so that the diameter of the radiating surface of the pn-overhang can be therefore compared to the known Lumineazenzdioften are enlarged. The enlargement of the area of the pn-Überp; angs in turn has a "., stronger P.elßstbarkeit and thus an increase in the achievable light output to the foI ^ e. · ·

As semiconductor materials for the light emitting diode according to the invention Gallium arsenide and gallium phosphide are particularly suitable. The semiconductor zones including the pn junction, which are used during "operation the light emitting diode are flowed through by the current and to Ensuring a high * "current-carrying capacity, only a low web resistance are allowed to have, are relatively highly endowed and non-resistive. They preferably have charge carrier concentrations

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of around 10 load carriers per era and more. For the essentially semicircular part of the semiconductor body adjoining one of these zones and having a lower charge carrier concentration, it has, in particular, a charge carrier concentration of less than

1 ß ^

10 load carriers per cnr proved to be advantageous. Because of diesel e very low carrier concentration will reduce the absorption of the

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Beam through free charge carriers in the hemispherical part dea Semiconductor body largely avoided.

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The "absorption of the pn junction emitted radiation in the tfbergang pn to the one of the two the enclosing Halbleiterzo- * NEN adjacent, substantially hemispherical portion of the Halbleiterkörpera can in the inventive light emitting diode by suitable choice of Qesaratstöratellenkonzentration, ie, the concentration of the acceptor - and Oonatorstöratelleri, are further reduced in the hemispherical part. The charge carrier concentration in the hemisphere is again less than 10 charge carriers per οπκ

■ 17 """ ³ p

selected as 10 'disruptions per cm'. The material of the hemisphere is thus only weakly compensated for in this embodiment of the luminescent diode. Due to the weak compensation, the absorption edge of the material of the hemisphere is compared to more strongly compensated material, i.e. compared to material with the same concentration of free charge carriers, iedo.ch a higher total interfering component concentration, and also compared to the more highly doped material that closes the pn junction «Tin + Semiconductor zones shifted in the direction of shorter wavelengths. As a result, at the wavelength of the emitted light in the material of the hemisphere, in addition to the already greatly reduced absorption by free charge carriers, the absorption by band-to-band transitions, eg Aryan interference bands, is also greatly reduced. In this embodiment of the luminescent diode according to the invention, the radiation emitted by the pn junction is therefore even less absorbed in the hemispherical part of the semiconductor body than in the embodiments in which only the charge carrier concentration is present

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in the hemisphere is less than 10 "charge carriers per cn '.

The erfindungsgemäßen.Lumineazenzdioden lasseh in accordance with the invention further advantageously prepared in the manner that a preferably fester einkri3tr.llinen semiconductor body with smaller Ladungsträgerkcnzentration a "low-half! ^ Hicht epitaxially aufgewaohsen. Is-then by diffusing dopant into the aufgev / achsenen Layer a pn junction at ⁴ ". Anno.hl comes alive-through toil.veine? Removal of the ridge grown on the surface of the pn junction; ve ^ Y-Λ ° inert and the final form of the hemiplegic body is produced by grinding. Nt ^ ^rl «r ready" + pI-lung des KalbleiterkörpeT '''.'- e ^ den the sharks, the pn-tfbe ^^ - jng enclosing shark b] egg terpenes nit suitable lock-free or; Y.on tv.k 'fnn mistaken .., ■ ·. · ■.

Del the making of the Lrrnines? En :: diodt ⁱ n karr a ^ cr. co ver.fchrsr .. '.verden that the Niederohfcige: 3chioht. riurcii Sindif f ^ r.dierori vo: i J-- fierstoff in a vorzu.gav / ei se oini-iria tull ^ .Men body; ^? - "i. ' de-.i semiconductor material with a small La-longn ^ rägerLonzyntr "· tion -obi 1: 1 et is. The pn transition is then formed in this low-resistance layer of a second dopant, which generates the opposite conductivity. Then ·; τ ^ ei '.' ^ H tei ^ - ice removal of the diffused layer which "Hnohe Inr, pn-i ^ Ker'-inn-o" is reduced. The further processing of the semiconductor '~ ö "oor ~ j kynr: d-Λπϊΐ as in the ent.i'enannton method er ^p o]. "n.

Both methods are particularly zv * Hn ^ s + el development oinnr YI number of light emitting diodes from "a one ^ i ^ ^ -en -rößei-en HmIbI ei ler

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disc. After the pn junction has been established in the nioderohtnifen 'layer, the HalMoite ^ noheibe can namely be divided into smaller Hai lead ter-'correr, which * .unn. individually processed into T.uTninesz ^ nzdiorlen.

The invention is to be explained in more detail in the following text on the basis of a few? I _{(tures. And examples.}

? ig. * 7ei ⁽ ; t r- ^ he'nnf.Rcr a Ai ^ fy.hrunpsheiapieü for a Lumineazen ^ diode remai? The invention

Vir ;. 2 be ^ t ^ chenatiach another Auaf'ihrMnrrbeispiel ff. '** a luminescence dic rerr> Mf? the invention no.

? 1 · ^τ . 3 shows Tohematir ^ e ^ ⁴ re Ausfrrun of the LED crcm / IOL sForm the invention, b-ei of special means to · "- KMhl.ung the diode vov'oaehen aind. . . ·

'i ??. Ä zei z \ gfhemn + inoh ein. '. Execution of the luninessence diode according to the invention with a special congestion of the hemispherical

for: iiren HnIblei ⁺ <
7i.?. ~ a to ^ς ε 2oif? en different stages, how the luminescent diode goes through "the Hsrst.rl Iunsr according to the inventive method. *.

In? If. 1 Let the simplest embodiment of the ⁷ vmineszenifiiode dcr <restcllt according to the invention. Between two low-resistance semiconductors " ¹ nn * ^Λ ? * ^R on ve» ¹ "? The type of conduction is radiation-capable; e nn-uberr-T. ^ r ^η ""<. Λη the semiconductor zone 12 borders the hemi -. 'Ol förTii ^ e part ¹ A. the öuf? a!. "aterial with a smaller charge carrier

n exists, then the radiation emitted by am.pn via ^ anr

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just sohwaoh absorbed. The pn junction 13 is located in a »cylinder-shaped ! »Igen elevation of the semi-conductor body. This ensures that the Diameter of the emitting surface of the pn junction small compared to the radius of the hemisphere 14 1st. On the semiconductor zone / M is a Block-free metal contact 1 "5 is attached. A wire-shaped lead 16 is soldered into each of these. For block-free contacting of the Balbleiterzane 12 is on this one perforated disc 17 from a suitable metal. By cooling this disc, .. at the same time that generated when the current flows through the light emitting diode

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ί heat dissipated

. Be ¹ I a preferred Ausftihrung3form of the LED according to the invention is "the hemisphere 14 made of high purity," a high-impedance, weak n-containing gallium arsenide with a total disturbance concentration

of less than 10 imperfections * prd * om and one charge carrier con «

Eentration of less than 10 charge carriers per cm ⁵ . The pn

transition, enclosing semiconductors attracted bind to the material of the Hemisphere grown epitaxially and also consist of gallium arenide. Zone 12 is low-resistance and highly η-conductive

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endowed. The impurity concentration is about 10 tellurium atoms per cm '. The fialbleltereone 11 let by diffusion of zinc atoms UBdotlert and p-type. The contact 15 is made by alloying an IndiuBipille in the zone 11. The metal disk 17 is made of tinned Kovarbleoh.

The described embodiment of the luminescent diode according to the invention made of gallium arsenide can be modified in various ways For example, dopants for the η-conductive half

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In addition to tellurium, the elements selenium, silicon and tin are also suitable for conductor zone 12. The non-blocking contact 15 can also be formed by alloying a zinc-tin alloy with a few percent by weight, preferably 5 percent by weight zinc, into the semiconductor 11. "There is also the possibility of forming the non-blocking contact 1-5 one made of silver or nickel layer existing Terzone _v on the semiconductor • 11 zudampf ene. the disc 17 may for example also. 'made of tinned or plated molybdenum sheet made. the Ladungaträgerkonzentration in the η-type region 1? may be advantageous.

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between about 10 and 4.10 load carriers per onr can be selected.

Pi ^. 2 shows a light emitting diode which is constructed similarly to I in Pir. T shown light emitting diode. In Pig. The embodiment shown in FIG. 2 is, however, not designed to be flat between the semiconductor part 12 and the hemispherical part 14. Rather, there is material with a smaller liadun.irst.rögerkonzentration to the p * n transition; The cylindrical projection is denoted by 21. Compared to the embodiment shown in Pig The chins are made thin, but all the absorption of the light shining into the hemisphere is mastered. Since the teeth on the sides of the cylinder-shaped bulge can be relatively thick, the path resistance is increased 12 not essential for this type of construction

The embodiment of the luminescent diode according to the invention shown in FIG. 3 differs from the type in "^ ig * 1 ^ ez-ed £ th

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through the power supply to the semiconductor zone 11. Ala power supply. A solid metal wire 31 'is provided, for example copper. In addition to the metal disk 17, this continuous conductor "31" can also be cooled, but the heat dissipation from the semiconductor material is improved and the luminescent diode can be earthed with higher currents. Diea has another one, F / rh ^ hun? Ae ^ Night performance to the pole: »e. · · · .. · ■ ■

.The in piss. 4 illustrated embodiment of the he ^ Lunvlneozenzdiorfe has a special geometric shape. "Her Halbleiterzorie 12 first lying absorbieren''p from weak;. N material with smaller-r Ladum / Kträjerkonzentration existing part of A ¹ is cylindrically formed formic j \ n di'eaen cylindrically crmirren part of the hemisphere 14 includes mi.t rleicher • LaiuriPintra / er ^ on ^ entrrj h'.on on. The height h of the cylindrical ^ part 41 int. Here ~, where r is the radius of the hemisphere 14 and η the refractive index of the r.yl ij -shaped part 41 'and the hemisphere means fourteenth the most pn ¹ 3 emitted radiation is due to the special shape * cs Hnlbleiterkörperg c bundled and leaves, the hemisphere 14 ire "" eoontl inhen in a direction '' the πehe perpendicular to the radiating Fl of the pn junction 1? Such a geometric arrangement is already known in another context under the name Weierstrass geometry.

r

became known.

As an example of the epitaxial growth process for producing de " According to the invention Lumineozenzdioden is based on the Pig; 5a to 5e show the production of several gallium arsenide! "the au« · one single semiconductor wafer described.

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In a ⁷ ! The first test step will be -iur> hoc ^; * ohmi re-n, ^ c ^ n - l ei ⁺ onden GnIl iu τι. ". ■" * - ^ '3 "id referring criat.-illine disc 5J with.

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a Tj'idun ^ str ^ rerkTr'Pn 'r ^r -ii on ^u on "" eni ^ r olr 1O per n' and.

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a Gespintstörsi eil ent-nnrpntr '-ti on from wenirt-r --.Io " ¹ O p.ro'enr' * er> i ⁺ ari'il * nit a ^ r low-ear ^ ui / ren, fH.-irk n-dofiert.on GalliumarBenid- "layer ', ->! 2 hesohi-ohtf- ¹ ,. ^ rr ^ v.-j ¹ ^ i the grill. 1 um ^ rsenid ^ cheibe- ^ ¹ and

^{; a} up GrIl i'j'nViri'enid ^rn .i ⁴ . a ^ r T-1 örs1ellenkonren + rvtion ptv> 2 ' ¹ O'Tell'ir'! ⁺ .f .'- ien per "T en in a 'hi ^ rzfimtvil] e. ^ e-

-nt, d <i die '.-, slice ^{c 1} and the ImII i um'irponid quell »:. · .η the ent-

Loose ends of the C'.uareinpulle. - ^ usBi.ylich is called

^m rMneportmit1el per cn ' de "· Ampullenvoluneno ¹ n.' ^r iodine in ^the; u ^r) ^ - ^ amnulle pinre just the AnnulIe -is d '\ nn evk'iieri and "u ^T ^ enohiüol- .en... Then "the part of the / -rnoulle that ^{contains -die R fi} lliumqr8enidqtielJe", nuf el'.va ¹ ποο ° Π and the part of the bearings that the. Disk * \ enninlt nu ^r etv: n BOO ⁰ C erl-it'.t. With the help of this as Transro ^ ⁴ mi t. te! at '; er ^: '.-i en Joden wird d '.' Vei GnIl iumarsenid. transported from the hotter to the cooler end of the luar ^ re vessel and avenges there : v. \ ^{r of} the disc ^C1 ulfi s ^H ark. n-doti er ⁺ e Gnllium ^ irsenidadhicb +. 5? epi '..' iviol T.if. Per Auf-vachpvor ^ anfi; v / ith by _cooling% rather ampoule na ^ ii about -1 hour terminated. Nsrh the duration of the stay hai the shift ^? a thickness of about ^Γ Ό p. The concentration of impurities in the

¹ 7 "5

oonich ^. amounts to about ¹ o l'ellurgtoine per cm. Plgi 5a

• i. the Gs.ll i'lmrsenide ^ is called " ¹ It the epitaxy! grown layer.

.. Tn a .r 'vei th Ver nhrensschri ^ i t is Eindif substantiate of zinc into the rail of the / Wfwachoschicht chich ^1, a pn-nn Überp provided semiconductor wafer within dor Aufv.'iichp ^; * prepared. To do this, the gallium red senide shell 7.-Jsn ^r amen ni-t 'nllischern Zin'x is placed in a quartz ampoule

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brings. The ampoule is evacuated and then heated abgesohmolzen and for about 1 hour at a temperature of about 900 ⁰ C. The zinc diffuses about 20 μ deep into the semiconductor body, so that a heavily p-doped layer 5? arises. In Fig.; 5b, the GaIliura arsenide disk is shown after this second process step.

Round cylinders are then punched out of this disk, for example with the aid of ultrasound, which are individually worked into luminescence diodes. Such a cylinder is shown in Fig. 5c. At the individual cylinders is then as shown in Fig. 5d shows, the * "epitaxially grown by about ³ HObleitefnchicht J ¹ It ζ s partially ebgetragen extent that def on the surface? Cylinder an approximately cylindrical-shaped elevation is created, at the beginning or in the interior of which the pn-transition runs. The part of the semiconductor body consisting of the weakly absorbing material is then ground to form a hemisphere. The two semiconductor zones 52 and Z3 are then, as already explained in connection with FIG. 1, provided with non-blocking contacts.

Because of the greatly reduced absorption, the hemispherical radii of the luminescent diodes according to the invention can be up to about 1 to 2 cm in size. The diameter of the radiating surface of the pn junction can be about half of the hemispherical shape, but is preferred

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Claims (17)

U89518 Claims Light emitting diode from a substantially hemispherical, one A semiconductor body containing a pn junction, the hemispherical radius of which is greater than the diameter of the radiating surface of the pn junction is, characterized in that in which one of the two den The substantially hemispherical part of the semiconductor body adjoining the pn junction including semiconductor zones, the charge carrier concentration is smaller than in the two semiconductor zones enclosing the pn junction. Luminescent diode according to Claim 1, characterized in that in the to the essentially hemispherical part of the semiconductor body adjoining one of the two semiconductor zones enclosing the pn junction the charge carrier concentration is less than 10 charge carriers per cm. Luminescent diode according to Claim 2, characterized in that in the to the one of the two semiconductor zones enclosing the pn junction, the essentially hemispherical part of the semiconductor 17th body the total impurity concentration less than 10 impurities per.cm is. Light emitting diode according to one of Claims 1 to 3> characterized in that the semiconductor body consists of gallium arsenide. Luminescent diode according to Claim 4, characterized in that the semiconductor zone lying between the essentially hemispherical part of the semiconductor body and the pn junction is η-conductive and New Documents (Art 711 Paragraph 2 No. <j fttg ^ p φμ ^ ψρρ. 4.9 . - 13 - Kb / Kö •: 1A89518 ■ 'p _LA C ^ -, _lq ^ v.'eif.'ep /.btraren of the grown up layer '.lie TMfirhe of the pn - about ~ ranges is reduced un ^ (let .ηη:? οη.1 ießeni · the semiconductor body is brought back to "its final full form" by grinding. A method of manufacturing 'n Luninenzenödiode. ° ch oinem of arrival "nriiöVie 1 to 8, characterized confess 7'ei c'rne t that, in a preferably einkriatalUnen semiconductor body with smaller Ladunrrt ^ aqerkon / ent ^ atioii' ¹ a ^ ent wei , Te ^ enf eoetz + e Lei tunp: st.yppn 'ereUc ^ ende joti erfsto'f ^ e are diffused in that by partially /. Erosion of the diffused layer the surface "of the pn-overronation created during the diffusion is reduced in size and d; 3 (3 is then brought into its final shape by grinding the semiconductor body. , .Method according to one of Claims 9 and 10, whereby * i: ekenn4iichnet, that the semiconductor grains after the herniation de? pn overranfree in smaller pieces is divided and that these are individually subjected to the further process steps. - .. COPY H 4 17 the Lad ian r ⁴ · ■ »'·"> -eriron ^ entrf? Tion .in dinner. Zone about 10' to 4-n T '"> d'} Γ! T -" «t7 *? 3 irpr» pt ·. '* T) ^ "Π t r *' ^ t« fii ''> d <'»rrv-h ciricn ^ cr" - "nrher ^ eKemien Anapri'ohe, ^ ° duroh r _iR i ₍ , -ic,:? ··» ·· η ο rh ..' ·] b ι1ν · ί3 ^τ Τ "1 b 1 ei tcr> körperä the part jait, · iHun" · ^ * "α ·· ρ r> on 'en ⁺ r ^ri ti .on ^ o ^n- en ien nn-UberrMJig hin -ayiin- d O ¹ ^ f """fTi""Vi" ·! '^!' ¹ "'Π ¹ ' ⁴ ". χ.τν- · ίno -``- pn ^ di ^ de nMrth f) .lno :. ⁿ . ^f ler ^ir or) _: he · 'ehen ^ -en speech, thereby. "• e ^: 'enn" ei chr.oT, d- "v? ^r1 he'Or den pn-! ' ^r ber ^ nri - ^ - including HaIh- Λ ei ter-Onen- ^r : A <■ m-iD ^o i ^<r on. ¹⁷¹ H * 'VörnenV: ^f> clock serving, aperrfrei- r ⁿ tr. ¹ J inchen Contacts-by mistake iiind. T.Mmine.Tzenzdi ode after a? ¹¹ de ** previous claims, daduroh ^; ^ ekenn.reiohnet. * 3 ^r i-3 "3er en dj e a H ^ .lbl« iterzone contiguous part of the semiconductors terlrö ^ perr rtit a smaller concentration of cylindrical shape ^ h in these zylinderförmi ^ s part of a HaihlcuR ¹ Cl with, same Ladun.'strä'jerkonzentration followed and ^ Fiss height en:? ^r "linde.r - 3 r" -eioh the quotient of your "radius * the Halbkurel and the Freohunroindex de? I * π. + Ο rials of the rr / linderfö ^ migen part and egg hkurel is "t. Procedure for. Manufacture of a light emitting diode according to one of the vorreher.den A-nsprflohe. d-adurr.h τ-ekonnze lohnet that ^ strägerkon to "a vnrzursvfeise einkriata] linen Hnlhleiterkorper small Ladim: ⁷ entration a more highly doped, niederohmj <\ e HalbleiterociJKicht epitaxially on ^ e-vichsen v / ith that substantiate by Rindif. from -tiotieratoff in the grown-up Gohicht a pn-transition is formed, "that through part- BATH ORIGINAL 90984470632 -Kb / Oa COPY