DE1964919A1 - Semiconductor light-emitting device and method for its manufacture - Google Patents

Description

RGA 61,580
TJ.S.Ser.No. 811,337
Filed: March 28,1969

ROA Corporation, New York, HY, V.St.A.

Semiconductor light emitting device and method for its manufacture.

The present invention relates to a light-emitting semiconductor component, in particular an injection laser that is able to emit coherent radiation at room temperature and is characterized by high power efficiency

To solve the problem of creating an injection semiconductor laser that can be operated at room temperature, A useful emission of coherent radiation at room temperature has not been possible until now, since the threshold current density at room temperature was typically 30 to 50 kA / cm and the differential quantum efficiency was relatively small. The upper limit of the quantum efficiency was previously 20 #. The main reason for the relatively low efficiency, the absorption of light in the material was adjacent to the active zones in which the laser effect occurs.

In the U.S.-PS. 3 309 553 describes a semiconductor laser that has injection electrodes with a relatively large band gap on either side of a thin zone with a smaller band gap. The thin middle zone forms the recombination area. In this known device, the carrier injection density is relatively large and it can be operated at room temperature with relatively good efficiency. The well-known semiconductor laser consists in particular of a three-layer arrangement with two gallium arsenide tubes, which are epitaxially grown on opposite sides of a thin germanium slice. With the known facility the active zone is not compensated.

009841/1618

BATH ORIGINAL

•• 2—

The present invention is based on the object, in the case of a light-emitting semiconductor component with two, epitaxially at one interface. coherent * semiconductor single crystal bodies, one of which consists of a material with a band gap that is at least 0.05 eV larger than that of the material of the other, the power efficiency at 30O ⁰ C. compared to known light-emitting diodes, which are at room temperature can be operated to improve and to simplify the production compared to the above-mentioned known semiconductor laser.

This object is achieved according to the invention in a semiconductor P component of the type specified above in that the other semiconductor body contains electrons in a concentration between about 1x10 and 5x10 cm, adjacent to the interface between the two bodies and a compensated P-zone and at a distance from the interface has an η zone which, with the p-zone, in which the defect electron concentration at the interface is approximately 1.5 × 10 ¹⁹ to 5 ₁ 0 × 10 ¹⁹ cm "* ⁵ , forms a pn junction that from the interface has a distance of about 1.2 to -3 "0 Aim"

In particular, the invention creates an improved semiconductor laser which contains two Haiti _e i-► j ter bodies which are epitaxially assigned to one another and connected at an interface. One body is p ⁺ -conducting and the other is η -conducting with a compensated p-zone adjacent to j the interface and a pn junction at the boundary · to the rest; the η-conductive body · The band gap in the p ⁺ -type pERSonal j by at least about D, conductive n-05 "V greater than the in:

Body. The concentration of the La- ι consisting of electrons

18 fertilizer is in the second body between about 1x10 >

18 * ^ 5
and 5 * 10 em and the defect electron concentration in the p-zone is at least in the part adjacent to the interface about 1.5 × 10 ¹⁹ to 3 »0 × 10 ¹ ^ cmT ⁵ . The pn junction is spaced from the interface between about 1.2 and about 3 »0 (.mu.m.

00 9841/1618 j

BATH ORIGINAL

The Irfindusg is explained in more detail ± m the following with reference to the drawing, for example, it shows:

1 shows a cross section through a part of a semiconductor laser * according to an example. of the invention and

Figure 2 · seheeatisehe a representation of an apparatus for producing this ^ä albleiter laser.

1 essentially shows the structure of a semiconductor laser 10 in accordance with an exemplary embodiment of the invention. The ^OB albleiter-Iaser is, there is a diode having a first body 12, the ζ · Β · tea Galliua-Aluainiumarsenid, and a second body 14, 4p z ·! · Gallium arsenide or gallium aluminum arsenide and at a Grenzflächt 16 lusaraeenhängt to the first body · the bodies 12 and 14 ^i: be associated with one another "pitaktisoh Ilen, ie a continuous Binkriatallstruirtur form * the body 12 k & m eg beet from a Epitaxieleehioht ■■; &% & $ on the body fourteenth 94 was formed vice versa '»The tipper 12 is p ⁺ -conducting. The body 14 was originally ga & s ή-> 1 aging, but has a p-zone 18 adjacent to the interface 16, which was preferably formed by diffusion of acceptors from the body 12. The zone 18 is therefore a compensated p- Zone · Between the 4 zone 18 and the η-conductive Best of the second body · 14, there is a pn junction 20.

The p * -2one 12 has a surface 22 on which one Metal layer 24 ^ finds, ie with the body 12 one ohmsohen contact aaaht. The ■ orper 14 has a corresponding Surface 26, which is provided with a metal layer 28 * The metal sheets 24 and 28 have connecting wires 30 or 52, the diode is connected to an associated one Circuit arrangement can be connected. The diode 10 can have cleavage surfaces, not shown, which have an optical Form a resonator "that contains zone 18"

4 pn-tlbergasag through. a geeignet® voltage at the 30 un * 52 !! "üriehtung yor _£ | * spe®s, '' I will be

009841/1818

Electrons from the η zone of the body 14 into the p-type Layer 18 injected. The indexed electrons recombine i & area. 1Θ emitting radiation so that the diode Highly emitted. At the tension that has to be exceeded the for. a laser effect required current post threshold is sufficient, the diode emits coherent radiation.

The mode of operation of the present component, in particular when it is operated at around 300 ° Kelvin, is influenced by various factors. One factor is the brad the difference between the crystal lattices of bodies 12 and 14 · The lattice undershoots should be small in order to reduce the stresses at the transition as much as possible. In addition, for reasons that will be explained, it is desirable that the band gap in zone 12 be substantially larger than that in body 14 *. This can be achieved by making body 12 from sallium-aluminum-arsenide and that the behavior! "of gallium and aluminum is selected according to the desired band gap value. The proportion of aluminum should not be too large, however, since deviations that are too great" occur between the crystal lattices between the bodies 12 and 14. It has been found that particularly Good properties can be achieved if the body 14 is made of gallium arsenide with a band gap of 1.43 V and the body 12 is made of gallium aluminum arsenide with a band gap of at least about 1.48 eV, but not more than about 1 _f 78 ef. Btid "bodies can also consist of Galliua aluminum ijreenid, and in this case the diameter of the body 12 would be at most O | 35 e ¥" larger than that of the body 14.

Other factors that influence the behavior of the semiconductor components in question are room temperature The difference between the sizes of the BsruSlüjfe in zones 12 and Η «dl« concentration of the ladimget / äf ^ «electrons in the

in ClQJT: -l.C ~: ** 18

Shafts result at room temperature when the band gap energy in zone 12 is at least about 0.05 eV. Volts is greater than in zone 14. Thus, if the body 14 is made of gallium arsenide (band gap 1.43 eV ·), gallium aluminum arsenide can be used for the body 12, which contains enough aluminum that the band gap is at least 1.48 eV. If the body 12 consists of gallium-aluminum-arsenide with the aluminum content x .. and the body 14 consists of gallium-aluminum-arsenide with the aluminum content X ₂ , XJ should be so much larger than X ₂ that the difference is inder Energy band gap at least 0.05 eV, is

The electron concentration in the body 14 should be between about 1.0x10 and about 5.0x10 om "* · ^. The defect electron concentration in the zone 18, at least in the part adjoining the interface 16, is between

1Q «Λ
see 1.5 and 5.0x10 um ^J and the distance t should be between 1.2 and 3 »0 um.

These parameters are all likely to make the particularly good properties of the present semiconductor component. The larger energy band gap in zone 12 results e.g. a refractive index in zone 12 which is smaller than that in zone 18 «The optical radiation generated in zone 18 is therefore largely reflected by the interface 16 and prevented from penetrating far into the adjacent material Energy losses through absorption are kept small by the fact that the absorption coefficient of the body 2 is small at the wavelength of the laser radiation due to its larger energy band gap compared to the body 18. The band gap at the interface 16 can also be one cause electrical limitation for the carriers injected into the zone 18 from the η-conductive part of the body 14, resulting in an increase in the profit of the facility

As mentioned, the behavior depends of the device 10 of the mutual relationship of the above-mentioned parameters from ·

009841/1618

"... ■ - ■■■ *" - ■ BAD. ORIGINAL

Sum example, small values of the distance t are desirable * in order to increase the transition gain, but on the other hand If the value of t is too small, it is undesirable, since a larger amount of the electric field at the transition into the zones will then be seen 12 and 14 can expand «If the values are too small, the yen t will In addition, the loading effect is unstable · In the ready to saturation of the output signal, large fluctuations in the output power can be observed. Presumably this effect depends together with the very high plasma current density that results from the electron influence due to the band gap difference at the Interface 16 results.

The semiconductor component 10 can be duroh epitaxial Crystal growth can be produced from the liquid or gaseous phase. Bas epitaxial deposition from the liquid Phase is preferred.

Preferably, the semiconductor component 10 is produced by a process as described essentially in the publication "Epitaxial Growth of GaAs and Ge from the liquid State and its Application to the Fabrication of Tunnel and Laser Diodes ¹¹ ," by H. Nelson in the magazine BOA Review, Volume 24 »\ (1965), pages 603-615 is described a device. for implementing this method is shown in Figure 2 sohematisch.

This device contains a boat 34 made of graphite, for example, in a quartz tube 36, which is shown in See known manner can be heated electrically. A substrate body, for example the body 14, is arranged in the shuttle 34, which is pressed firmly against the bottom of the boat by a clamp 38. The quartz tube with the shuttle 34 is initially tilted a little, as shown in Fig. 2, and in the lower part of the shuttle there is a throw ze 38 of the desired crystal material and the appropriate dopants in a solvent. An oxidation To prevent in the area of the substrate 14, an inert gas or hydrogen stream is passed through the tube 36.

The shuttle is made with a number of components

the melt 38 and with the clamped substrate 14 in the bore

OQ9841 / I5ia

ORIGINAL

10649T9

36 arranged and the Sote id.?d then in the tilted instant, as fig · 2 tends "on tine suitable for crystal growing !! temperature" rhitst * While the temperature in Hohr 36 rises "solmiliüt das Loeuageaiitti :! When the various substances ions see the temperature in the ^{West known as "Eipptemper & tur 11} ", the heating is turned off and the Eöhrt 36 is tilted so that the melt 38 is exposed over the surface v The substrate surface 14 flows and this covers it. At this stage the solvent is almost saturated with the desired crystalline file, according to the abbot

cool j d "e * furnace solves flee safsiiglieh some material from the surface d j ·" substrate _"f Ms eir. Iet reached Ii8sungsgleichg © wieht ~ leg further cooling falls ü »Wed the gewünoCi · '^ material from d * r X (t} euag and it will find sia" pitaktisehes E istallwathstum au vi in Substmt place "IfaeMsm dl © Epitaxialsohioht 4i" gewüneeiit * "£ 1 · ϊ £% Qrv; $ tihX la & tf the Boäir 36 will be again in« Aofa & f ^ lgvif su.H "·· - * - and dis restlioae melt ^;

rtl & zht ^A. λ, -i «* t · W« na the tilting temperature ί hoeh gew ^ el: 13 * S, kmm * i © g «S © ae 18 gleioh- '" it dem Wftohetuia ütv Zcim 12 dif.fimaic ^ s become · When tilting "" p # r & tur can other "2? Seita auct sisf ^ erMlltsiemäSig

Value h beu, and, DI® after Beeüdiguag cloe Äufv /-axle lpitaxialkörpars resulting Anordmmc can then for • ine from "ldhenie time he & i1,? St _s weffäen the zone wm 18 axucoh diffusion of Dotis-susgg ^^ ffe & tea pS ^ ps from the p * «Zone 12 iu er« e ^^> ·· &, In - ^ 'Sidf ·: ^ allen soll file Mffusicneaeit eo beaessan wera®?. ^ that 6er 1 tand t awisehsn I ₆ , 2 nsd Jj becomes large «

In the following there are examples of sp © siell ©

falii ^s explain
Q ₃ eondsrn

£ rietffill8üc;:%, ing »f» yfalii ^s it explains, dl © ai

l »the £ - ;;» töa 'it ^^ tomgM ^ sL ^ -ii © alt · v -: - n' dc, ::.

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19649Ϊ9

Example I.

A ρ ⁺ -Ζοη · 12 is produced by epitaxial crystal growth from the liquid phase starting at a tilting temperature of 930 ° from a melt consisting of 10 g gallium, 1.7 g gallium areenide, 12 mg aluminum and 0.3 g zinc consists. In this example, the zone 18 is formed during slow cooling τοη 930 ⁰ O by diffusion of zinc from the p ⁺ «-conducting body. The substrate 14 on which the body 12 grows consists in this example of a disk which was cut parallel to the f100l crystal plane from a silicon-doped, η-conducting Gallium arenide single crystal. The gallium arsenide single crystal was through the Bridgman crystal growth process has been established.

In the resulting component, the distance t between the interface 16 and the pn junction 20 was approximately 2 μm. The defect electron ^{concentration in the p +} -zone was et-

The electron concentration in the substrate 14

The energy band gap in the n-conducting body had a value of 1.43 eY. and in the p ⁺ -conducting body 12 at or near the interface 16 the value 1.65 eV

wa 2x10 ¹⁹ cm * " ³ was 2.5x10 ¹⁸ cm *" ³ .

Example II.

In this example, a p ⁺ zone 12, beginning at 930 ⁰ O, was deposited from a Sohmelze which contained 10 g of gallium, 1.7 g of gallium arsenide, 6 mg of aluminum and 0.35 g of zinc. In this example, there was less aluminum in the gallium-aluminum-arsenide body 12. The substrate 14 again consisted of silicon-doped gallium arsenide, but in this example the electron concentration in the body 14 was about 4x10 cm * "* ^{3 +} Body 12 about 2.5x1O ^ cjh * " ³ and the energy band gap in area 12 near the limit fί- v _s .6 about 1.5 eV.

009841/1618

BATH

Example III

In this example, a p ⁺ body 12, beginning at the somewhat lower temperature of 900 ° O, was deposited from a melt which contained 6 g of gallium, 0.65 g of gallium arsenide, 5 mg of aluminum and 0.2 g of zinc. The substrate consisted of gallium arsenide doped with iellurium with an electron concentration

1 ft ^

tration of about 4x10 em. Mach completion of the epitaxial crystal growing the disc and 0.007 g of zinc arsenide in an evacuated ampoule was heated ablated long as at about 85O ⁰ O until the thickness t of the diffusion zone had its optimum value. The heating can take about a quarter of an hour, for example, a value of 2 µm being obtained for t. In this example, the energy band gap in zone 12 at or near interface 16 was about 1.57 eVe and the defect electron concentration in the zone

19 "· 3 '

was about 2.5x10 cm at the interface 16 ",:

Example IY j

In this example, both the body 14 and the p ⁺ -type region 12 were formed by epitaxial crystal growth from the liquid phase. The body 12 was grown on a gallium arsenide substrate with the orientation fiOOj and a defect electron concentration of about

19 «- ^
1 j 5x10 cm formed. The Epitaxialsohioht was deposited starting at 880 G ⁰ from a melt containing 6 g of gallium, aluminum and 15 mg Oj2 g containing zinc. After formation, the epitaxial layer was determined by lapping to a thickness of 25 <abgetrogen and then to the body 14 was deposited on the lapped surface beginning at a! Temperature of 92o C ⁰ from a melt, the gallium 6 g, 0.75 g Contained gallium arsenide, 3 mg aluminum and 2 mg tellurium. In the resulting component, the distance t was about 1.5 ^{μm, the defect electron concentration in the p +} ~ body 12 about 2.0x10 ca, the electron concentration in the body 14 about 1.5x10 cm, the energy band gap at the pn junction about 1.5 eV. and the energy band gap in zone 12 near the pn junction

009841/1618

BATH ORIGINAL

about 1.55 eV "

Injection laser manufactured in the manner described above were able to use current diabetes thresholds at room temperature operated, which were at least a factor of 2 smaller than the known injection ^ lasers same dimensions. The efficiency of the present facilities is at least a factor greater than that of the known facilities · The present facilities could be at or near room temperature continuously operate.

0 0 9 8 41/1618

Claims (1)

Patent claims IJ Iiiohtemlttierendes semiconductor component with two at a boundary epitaxially connected semiconductor monocrystalline bodies, one of which consists of a material of a band gap that is at least 0.05 eV. Gröfler than that of the material of the other, gekennzei characterized without t, that the other ^H albleiterkörper (14) Uektronen in a concentration between about 1x10 and 5x10 contain em * 'and ansohliessend to the interface iwlsohen the two bodies a compensated p-type region ( 18) as well as at a distance from the interface (16) has an n-zone which forms a pn-junction ^{with the ρ-zone, in which the defect electron concentration at the size area is about 1.5x1O 19 to 0x10,} which has a distance of about 1.2 to 5t0 fern from the boundary surface « 2. Semiconductor component naoh claim 1, d a you r ο h characterized that the second body consists of (Jallium-AreenidL and that the first body is an EpI-taxialsehioht made of Oalllum-Alumlnium-Arsenid, which on a The surface of the swsiten body was formed is. 3 · Semiconductor component naoh claim 1, since you raw gekennseiohnet that the first body from ^! Oallium-AluHiinium-Areenid with a given aluminum content (x ^) and that the second body consists of gallium-aluminum-arsenide, the aluminum content (x ₂ ) is less than that of the first body 4 Semiconductor component according to claim I ₉ identified by an electronic body (14) made of η-conductive semiconductor material, in which the concentration of the carrier electrons is about 1x1O ¹⁸ to 5x1O ¹⁸ OmT ³ , a diffused P-zone (18), which in this body ( 14) adjacent to one of its rare sites and forms a light-emitting pn junction (20) with the rest of the body, 009841/1618 ORIGINAL its distance from the mentioned side of the body about 1.2 to 3jOfUm corresponding to a concentration of! Defect-1 IQ 1Q - ^ 5 electrons between about 1.5x10 ^ and 5 * 0x10 * em in this one Side is, and a single crystal body (12) made of p-conductive semiconductor material, which on the mentioned side with the first body (14) is epitaxially related and has an energy band gap which is at least 0.05 eV greater than that of the first-mentioned body. 5ο semiconductor construction element according to claim 4 »thereby characterized in that the erete body is made of GaI-t lium jirsenide and that the p-conducting body is made of galium " Aluminum arsenide is made up of so much aluminum that the band gap between about 1.48 and 1.78 eV. amounts to. 6ο semiconductor component according to claim 4 »thereby characterized in that the first-mentioned body is made of gallium-aluminum-arsenide with an energy band gap between about 1.48 and 1.73 eV. and that the p-type body is made of gallium-aluminum-arsenia with an energy band gap between about 1.53 and 1.78 eV. A method for producing a semiconductor component according to claim 1, characterized in that an epitaxial layer of single crystal material is formed on a surface of a body made of another compatible single crystal material, one of the two materials being D-conductive and a defect electron concentration between about 1.5x10 - ¹ and about 510x10 cm and an energy band gap that is at least 0.05 eV. is greater than that of the other of the two materials and the other of the two materials is η-conductive and has a carrier electron concentration between about 1x10 and 5x10 cm, and that the layer and the body for such a time and at such a temperature are heated so that acceptor impurities from the p-conductive material diffuse into the η-conductive material and form a pn junction in it, which in 0098M / 1 0 1 8 ßA ORIGINAL a distance of about 1.2 to about 3 »O µm parallel to the mentioned Surface runs. 8. The method according to claims 7 »characterized in that that an epitaxial layer of gallium-aluminum-arsenide formed on a body of gallium araenide will. 9. The method according to claim 7i, characterized in that gallium-aluminum-arsenide are used both for the body and for the epitaxial layer, the aluminum consentration in the material of the p-! Yps being so much higher than in the material of the n- _{53yps f} that the band gap is at least Q _s 05 eV _o greater. 10. The method according to claim 8, characterized in that that the growth of the epitaxial material and the heating are carried out simultaneously by the Epitaxial layer from the liquid. Phase at a lip parting temperature is boiled from about 9? 0 ° U » 11. The method according to claim 8, characterized in that the epitaxial layer is deposited from äss liquid phase at a tilting temperature of about 930 and that the heating is ^{carried out at about 85O 0} O and takes about half an hour <, 0 0 9 8 A 1/1 6 1 8 Blank page