CA1043894A - Electroluminescent device of heterogeneous structure and method of manufacturing same - Google Patents
Electroluminescent device of heterogeneous structure and method of manufacturing sameInfo
- Publication number
- CA1043894A CA1043894A CA226,180A CA226180A CA1043894A CA 1043894 A CA1043894 A CA 1043894A CA 226180 A CA226180 A CA 226180A CA 1043894 A CA1043894 A CA 1043894A
- Authority
- CA
- Canada
- Prior art keywords
- layer
- epitaxial layer
- zone
- region
- junction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004519 manufacturing process Methods 0.000 title description 5
- 239000000463 material Substances 0.000 claims abstract description 27
- 239000004065 semiconductor Substances 0.000 claims abstract description 9
- 238000009792 diffusion process Methods 0.000 claims description 21
- 229910052733 gallium Inorganic materials 0.000 claims description 11
- 239000000758 substrate Substances 0.000 claims description 11
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 10
- 239000000969 carrier Substances 0.000 claims description 9
- MDPILPRLPQYEEN-UHFFFAOYSA-N aluminium arsenide Chemical compound [As]#[Al] MDPILPRLPQYEEN-UHFFFAOYSA-N 0.000 claims description 6
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 claims description 5
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims description 5
- 230000000694 effects Effects 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 description 8
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 7
- 238000000151 deposition Methods 0.000 description 7
- 229910052725 zinc Inorganic materials 0.000 description 6
- 239000011701 zinc Substances 0.000 description 6
- 230000008021 deposition Effects 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 230000000873 masking effect Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 244000228957 Ferula foetida Species 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000002800 charge carrier Substances 0.000 description 2
- 238000000407 epitaxy Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 210000003127 knee Anatomy 0.000 description 2
- 238000005036 potential barrier Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- NSMXQKNUPPXBRG-SECBINFHSA-N (R)-lisofylline Chemical compound O=C1N(CCCC[C@H](O)C)C(=O)N(C)C2=C1N(C)C=N2 NSMXQKNUPPXBRG-SECBINFHSA-N 0.000 description 1
- 241000234282 Allium Species 0.000 description 1
- 101150039167 Bex3 gene Proteins 0.000 description 1
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 1
- 101100491149 Caenorhabditis elegans lem-3 gene Proteins 0.000 description 1
- 101100270435 Mus musculus Arhgef12 gene Proteins 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- CEJLBZWIKQJOAT-UHFFFAOYSA-N dichloroisocyanuric acid Chemical compound ClN1C(=O)NC(=O)N(Cl)C1=O CEJLBZWIKQJOAT-UHFFFAOYSA-N 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 235000019557 luminance Nutrition 0.000 description 1
- KRTSDMXIXPKRQR-AATRIKPKSA-N monocrotophos Chemical compound CNC(=O)\C=C(/C)OP(=O)(OC)OC KRTSDMXIXPKRQR-AATRIKPKSA-N 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/0004—Devices characterised by their operation
- H01L33/002—Devices characterised by their operation having heterojunctions or graded gap
- H01L33/0025—Devices characterised by their operation having heterojunctions or graded gap comprising only AIIIBV compounds
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Led Devices (AREA)
- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
Abstract
ABSTRACT
An electroluminescent semiconductor device of a heterogeneous structure comprises a body of at least one material having a first forbidden bandwidth and having electroluminescent properties and an epitaxial layer of a material having a larger forbidden bandwidth. The body comprising a p-n junction in the proximity of the interface with the epitaxial layer. This epitaxial layer is of the same conductivity type as the body and the device comprises a flat region which has been diffused from a surface part of the outer surface of the layer with a conductivity type which is opposite to that of the body and of the layer. This region extends from the surface down to a depth exceeding the thickness of the layer.
An electroluminescent semiconductor device of a heterogeneous structure comprises a body of at least one material having a first forbidden bandwidth and having electroluminescent properties and an epitaxial layer of a material having a larger forbidden bandwidth. The body comprising a p-n junction in the proximity of the interface with the epitaxial layer. This epitaxial layer is of the same conductivity type as the body and the device comprises a flat region which has been diffused from a surface part of the outer surface of the layer with a conductivity type which is opposite to that of the body and of the layer. This region extends from the surface down to a depth exceeding the thickness of the layer.
Description
P~. 74-540.
3~
.... ... ..
"Electroluminescent device of heterogeneous structure and method of manufacturing same".
~,,", me present invention relates to a semiconr ;~ ductor devioe of a heterogeneous structure and compris-ing an electrDluminescent diode having a body of at least one material having a first forbidden bandwidth - ' and electroluminescent properties and an epitaxial layer of a material having a larger for~idden band-width, the said kody having a p-n junction in the proximity o~ ths intexface with the said layer.
e present invention also relates to a 10 ~ method of manufacturiny said electroluminescent de-vloe.
Electroluminescent diodes are knswn having a semiconduc*or junction~which use the sorcalled "oonfin:m~ne effect" of the charge carriers. me ; 15 ~ confinem nt, in the reccmbLnation region, of the minority charge carriers which are injected in a diode having a ~n junction results frcm the presence o~ a pstential barrier which endea~Durs bD ~oroe said . ~ , ..
carrier~ back. The~potential barrier is obtained ky nanufaotDring a hetl~sxeneous structure with a layer ~;
o a material having a larger ~orbidd~n bandhldth -~
han that of t;he material of ~he bo~y on which said layer i~ deposited. Elec~rolu=~nescent devices o~
.: :
~ 2 ~ ~
;.~~ , . ' ' ;~ . :
PHF. 74-540.
9~ ~
this type are described in the Uhited States publica-tion "Proceedings of the IEEE", August 1971, E~
1263 and 1264.
For the manufacture of said devices there is deposited an epit~xial layer of a conductivity type which is opposite to that which serves as a substrate, in which the active junction proves to be ;-; foroed back into a substrate, either by diffusion in-; to the latter before the deposition of the layer, or ~ 10 by diffusion of doping Lmpuritieis in the layer durLng -'~ the epi~axial grcwth. However, said devices have no localized junction. The emission region proves to be limited oMly by measures in thie field of shape and cont-~ct, which prese~t difficulties~in~the perfornance.
;}5~ The coupling with an optical fibre does not give~sati6-faction, the coupling surface is not sufficlently flat,~
the~emissive;~surface is not readily~defined.~ In ad- -dition,~the~emitted~rad1 tio~ ~ouId~traverse a comr ti~ely thick region of the body, so of a~material 20 ~ having a small forbidd0n bendwidth, whose abrorption is not negligible.
On the other hand said devices have a junction which is at the same level as a s1de sur- ;
face or other surface of tha cryst~l and thus con~
stitNte plaoes for surface current~ having non-radia~ion re~mbinations~and a reduction of tha lu-rinLrus e~llolenoy.
.. ,,. , ~ .. , P~. 74~540. '''' ' ''.
. .
~ ~3~9~
A spPcial object of the present invention is to mitigate the said drawbacks and to provide and elec~
trolum mescent device which uses the confinenent effect ' ' of the minority carriers which are injected into a '~
diode of a heter3geneous structure and which shcw a ~; readily localized emissio.n, if necessary of a very ' ~ small surface and a large luminous efficiency. : '' Y According to the invention, the semiconduc- '' tor device having a heterogeneous structure and com~
1 10 prising an elsctroluminescent diodb having a body of .:
! : at least a material having a first forbidden band-width and having electroluminesc~nt properties and ,.
an epitaxial layer of a~mYterial having a læger '. ' : forbidden ba~dwidth, the said body havdng a ~n : . ' .15~ nctlon~in the'ploximdty of ~he interfaoe wi ~ the~ .
said layer, is chararterized'~in that, because the' said epi~ax1al layer'is~of~the'same cDnductivity ~ .:
kype as the said body, said device ccmprises flat .
regic~ ~ ich has been'diffused fr~m a surfxcx~part ;,' 20:. :: of the outer ~urface of the~said layer with a oon- .;
ductivit~ type which is opposite to that of the ., :: .
bcdy and o~ the la~er, said r~ion ex*ending from the emissive sur~ace of the device dcwn to a dep~h .; ;~
: which is~larger ~han ~he thickness o~ the said - .
layer.
The di~fus:l region of which the oonduc- ~
~',::' ~ ~ . :: :
4 - :
:1 ~: ' , i: .
i, .
'; PHF. 74-540.
. ~ .
31~9f~ ~ -tivity type is opposite to that of the body comprises in the epitaxial layer two parts: a part having a ;~'larger forbidden bimdwidth and in the body of the de- ~ ' '' vice a part having a less lar~e forbidden bandwidth.
-j 5 When ~he device is polarised in the forward direction, ' the m~nority carriers are subjected to the confmement effect m the thickness of the part having the le~s ; -'' ;!,,.; large forbidden bandwidth, they are ~orced ~ack by --` the potential barrier which forms the inter~ace ke~
;;;, 10 b~een the tw~ parts, hence a very larg~ vDlume effi~
;~ ciency. ' The device acoording~to the invention is in ; '' the'form of a flat structure the'surface of which is ''~' readily suitable for posiflocing the end of an o ~ ~
~ ~ cal fib~e beam. me actave électr~lu~inescent règion ` is diffused and the conventional methods of masking~
and~diffusion enable the'f.~nufacture of diffused regions on the'readily limited'regions, if necessi~ry J ~ ~ on the very small regions whlch facilitate the 20~ coupling to an optica1 fibre. ~' ; The e~rfaoe c~rren¢s which in~Dl~e non-radiation reoombination æe strongly reduced rela-' tive ~D those in the kncwn devices. If actually the ch~¢arteristic curve of the current is oonsidered ' 25~ as a function of the applied v~ltage in the forward direction o~ the device, it is seen that t~e ~Dltage o the surace part of the junction o~ the device ' ~ ' , " - S - ;
,,~ .
~; PHF. 74-540.
. , ~04~B~4 ~ which is present in the epit~xial layer is higher ~han ; the knee voltage of the deep part of said junction .~
which is present in the body made of a material having ., j .
a smaller forbidden bandwid~h, said seoond part of the , 5 j-mction corresponding ~o the electroluminescent .,~ , , active region. With supply vDltages exceeding the knee- voltage of the deep part, the current through the surface part may be neglected as co~pared with -that through the active part of the junction.
In a preferred e~bcdIment the diffused re-gion of the device of a canductivity type opposite to that of the body and of the epltarial layer oom~
prises several zones:~ a principal zone ~he deep part ;~ of:which is elsctDol D sscent and the oonosntra ~ n 15 ~ ~; of doping irpuritiss of which~is sd3çted~to said =ctlon, and a surface zone whi~ adjoins the prinr cipal zone ~nd of which the depth is smaller than l~ the thdckness of ths epitaxial layer and the co=ccnr tration of dcping irpurlties of which is adapted ~i$;; ~ ~ 20 ~ ~ for making~gupply cont30ts and for that reason is ;
oc~parativ~ly high.
The sur~ace~o~ theisurface zone prD~ect- ~i mg beyond that of ~he ~rincipal zone, it is pos-sible to use same fox makLng~a su~ficientl~ large 25~ surfaos oontact withDut using ~or that purpose a part of the emissive surfsoe o the principal zone.
~ ~ princlpal~zone on~the one side and the surface ~ -;3~
,i,~ ' .' , '.
~, : ~ :
PHF. 74-540.
'.
zone on the other side may have optimNm defect con-centrations without a compromise or a complicated concentration profile being necessary. Further~ore, on the one hand the part of the diode which corresponds;
to the surface zone adjoining the principal zone has a higher knee voltage than the emissi~e part of the diode and on the other hand has a lower series resist-ance due ~o the doping~ with high concentration, of the zone destined for the contact. Thus the active part of the diode is protected from tco high current strengths in the forward direction. Because the con-centration of doping impurities of the contact zone ;~
~ is higher than that of the ac*iv~ zone, the~breakdcwn !
'! voltage in the reverse direction is lower and the ,~
~;~ 15 actlve part of the diode is also protected fnom pos-; sibly oocurring reverse vDlta~es.
~1 . . , The thickness of the active region, or the region in which carriers are confin3d, taken between . i ~ . ; ; .: .
the surface of the junction and the interface be~ween ! 20 the substrate a~d the epitaxial layer, is determined as a function of the av~rage diffusion length of the minority carriers in the material of said region. The ! ~ ~ thickness of the active part should be so much lower ~ ~
¦ than ~he diffusion length that the possibiiity o~
~; ~5 radiatlng reoombina~ions in said region is maximum.
The ~hickness of the active region, taken between the 1 ~ junction and the interface preferably is between hal~
.',~, , - ..
PHF. 74-540. ~ ~ ~
8~ ~
and the hundred~h part of the average diffusion length ~ -~
of the minority carriers in the material of said ~ active region.
.. j . . .
~`i In an example of the device according to the ~ -`~ 5 inNention a substrate of gallium arsenide of the '` nrconductivit~ type oomprises an epitaxial layer of i the same conductivity type of galliumaluminium ar-21x~s, x beLng between 0~05 and 0.4 and ;
preferably beingsequal to 0.1. A localized diffuS^~ed 5~ tO region which is doped with: zinc in such mannar that it shows the E~conductivity type penetrates into~he~
layer and into the~substrate.
In~anothsr enbcdiment a device according ~ `~
to~the inventlcn comprises~a body ~oraed by~a pas~
15 ~ sive substra~e of a~natsrlal~ha:v mg~goDd nEohanical ies and ninimum~cost whi~ls~oovered with ;an epitaxisl layer of a mbkerial which can be db-posited m good~epitaxial conditions on the said sub-strat2~and which has m pYrtlcular been-chosen to be ;20~ so that~the intsrfsoe between said layer and the ep~ W layer o~ a material having a larger ~ox-bidden~;bar~width ha~ the best elsctrDnic properties and the best behaviour with respect ~o the mechanical and thllmal stressas to~whlch the devics may be sub-25~ jected d~ ing operatian. ~or example, the devica has been mQde of~a substrate o~ ~allium arsenide ha~ ng a layer o~ gallium and alumindum axsenide Gal- ~ yAs~
, .. .. .
PHF. 74-540. ~. .
38~
which is covered with a layer o~ gallium and aluminium arsenide Gal xAlyAs, in which x > y, the layer and the . .
first layer of gallium and aluminium arsenide being of the sam~e conductivity type as the substrate c~nd has a region diffused from the outer surfaoe of the epitaxial layer formLng a ~n junction of which the active flat ~ -: part is present in the said layer. Actually it is : .
kncwn that in the epitaxial conditions of the known methods an Lnterface between galli~m and aluninium ... :~ :
arsenides of different cc=}o~itions is of a better ..
quality ffhan an interface betwe~n gallium arsenide .
and gallium;c~nd aluminium ~rsenide, the deviation in composition being~of the same order in~bo~h cases.
: PurthermDre, in~applications;such as~phDtocDuplers 15 ~ or in op*icaL~teleoDmmunication the emLssive~spec~
trum of the~di ~ :according:to said last enbofiment :
on~the one~hand oorrespocds particularly readily to the transparent window of the transmission ~ . :
of the opkical fibres which are ~sually used in said ' ; .;
20 : ~ applicaticms, on the other hand 1n~D1~ss a bettér ;.
absorp~ion of the photon~ in the pbGtormDsiver o~ .- .: .
photoreceivers con~sntionally used in said applica-tions. ~
Plthcugh it is possible tD use a de~ioe 25~ aco~rding to~the irvention ~n whidh:the light rela~
tive to the epit~Yial Iayer m~mates:throLgh ~he rear face of the body of ~he device, if ae5ired by provid- .. ;
. ~ ~ : : .. . .
~: : .: ' ' -:
~: . .
PHF. 74-540.
,. ' , .
~ 4~B94 ` - ~
~ ing lccally a reduction of the thickness of the body, ~ it is recommendable to use it in such nanner that the light emanates from the outer surface of the epit~xial ~? layer beoause the absorption in said enission direction ~t . 5 is miDimum.
;l m e present invention also relates to a methcai .,j , .
:.~ of nanufacturing a device as described above.
;1 . According to the Lnvention, the method of manr ufacturing an electrolr~dnescent semiconductor device of a heterogeneous structure, aco~rding to which an ~ ~-epitaxial layer of a semiconductor material of a first forbidden bandwidth lS deposited on a body of a rKterial having a ~maller forbidden bandAidthi in whioh :
a E~n junction is formed in the said device near the 15~ interE~oe bKt~een said latter and the deposited~layèr, ~ -'~? ~ : is dharactKrized in~ha~.t~e said epitaiial layer i5 '. ' ' .
deposited with:a doping which gives it the same conr ductivity type as the~said laye~r and that after~the epitaxial deposition~a doping impurity is diff~ed 20~: ~ron a local ~urface on t~ie outer surface of the said layer which gives it the opposite oonductivity type dcwn to : a depth which is slightly larger tha~ the thickness of the ::.
` 9aid layer. : ..
. . Because the epitaxial layer is o~ the sa~e 25~ ccndh~tivi~y type~as the bcdy on which it is de- .-.
j; : ., ~! .~ - . .
-- .
'. i ~ ~ ' ' ' ; ',~ ~ : ' ':
'.~/ ~:-~: ;. "'' '. , ,' ' ... ', ", . .'"i,,., ' ', , ' . : ' ', ' ' '' ,' , . " ,, ' : .
PHF. 7q-540. ~
38~
posited, no diffusion occurs in which the conducti-vity type of the bcdy in the proximity of the inter-faoe can invert, neither during the deposition nor thereafter. It is possible to determine an optimum junction aepth without being dependent on the condi-, tions in which the epita~y is carried out: the !
junction depth is determined only by the conditions - -'! of the fm al diffusion and especially of the duration ~, .
;, of said operation.
Ihe diffusion from the Æ faoe can easily , be localized by the masking me~hods conventionally used in the m~nu~acture of semicondhcbor devioe s of .~ .
the flat type. With this n#thod very small junction surfaces can be delimited, for exdmple, with a 15 ~ diameter in the order of a few micrcmeters. me :
method er~hles-the`manufa ~ e of mosaics of a~y oon-figuration and di~ensions coeF3title with available semiconductor plates. .
Asoordin~ to a preferred enbodiment of the 20 ~ methcd acoordLng to ~he`invantion the epitaxial de-po~ n of the layer of a material havin~ a larger ~ ;
forbidden ban~width i9 carried out, a~ter which a ma~3k of a d~nse ma ~ rial is manufac~red on said layer and a doping impurity is diffused through the -25 ~ ~ a~pertur2s of said mask for the`necessary time, which inpurity c~n reach and~pass the interface between ` ;
the depo9ited~ layer and the body which has served .,.
~ PHF. 74-540. ~i as a substrate. For e~ample, when the bcdy is of n-type gallium arsenide, an epitaxial layer is depc~
sited of gallium and aluminium arsenide of the n-type, a masX of silicon nitride is manufactured by deposi-S tion and photoe~hing and zinc is dif~used through the aFertures of the mask for such a lcng period of time that a concentratio~ is obtained which gives the material the ~type dcwn to a depth which is larger than the thickness of the epitaxial layer.
A second diffusion of a short duration is pr~¢erably carried out which gives a maximum surface ..... ..
conoentration and a mLnimum junction depth acoording -to~a surface which pLo~ects far beyond the pre~eding diffusion surface, the extra sur~aoe being destined tD receive oontact me~ns in t~ ~o~m of a localized ~ ~ -me*al deposit. The~seo~ difusion is preferably nade with the same dcpdng i~purity as the first diffusion and by neans of a mask which is obtained, f~r example, by deposition and photoetching.
0 ~ me seoond diffusion may either ocver the first diffusion 70ne entirely or relat~ only to an annular Æ face or only a surface adjoining that of ffhe first dif~usion in such manner that the radiation abrcrption mmi ted du~t~ the central zone present 5~ ~ ~ abcve t~le emi aion regicn is reduced.
The ir~uentian may be u~ed for the m,~nufac-ture of eleotro1umincsoent devices, ~or example, r: ~ ~:
) ' ~ . ' 7 ~
~ 12 -s~
~:
PHF 74,540 . . .
diodes, destined to be coupled to photosensitive de~ -vices, in particular by the channel of optical fibres.
The devices according to the invention are preferred for uses in telemetry and optical telecommunicat;on, especially by means of optical multimode fibres.
The invention will be described in greater detail with reference to the accompanying drawings.
Fig. l is a diagrammatic cross-sectional view of a first embodiment of a diode according to -the invention.
':! Fig. 2a to 2f show the various stages of . ' . .. .
, the manufacture of the diode shown in Fig. l. - , Fig. 3 is a diagrammatic cross-sec~ional ~ view of another embodiment of a diode according to ;3~ 15 the invention. :
: .
~ Fig. 4 is a diagrammatic cross-sectional ~ ~ ~
, :~ : ; . ,.- . . .
view of a th1rd embodiment of a diode according to the invention.
Fig. 5 ~is a diagrammatic cross-sectional 20 ~ ~view of~a fourth embodiment of a d10de according to ~ ;
the invent10n.
The diagrammatic cross-sect~onal v~ew of F-3g. 1 shows a d30de which is manufactured accord3ng I to the method of the invention and which comprises a' ~ ;;
25 ~ sem~3conductor body l wh~3ch is covered dn one of the ; surfaces thereof with a layer 2 of another semicon ; ductor materia1 having a larger forbidden bandw~dth ; than the material of the body l. The body 1 and the 3~ ~ layer 2 have a crystal latt~,3ce of the same type and ~3~ 30 have constants the values o~ which are close together, ;,3~
l3 .,.
't .. .. ... . . . . . .... ... .. .. ... . . . . . . . .. . . .
PHF. 74-540.
the lattice of figure 2 elongating that of figure 1.
The materials of the body 1 and of the layer 2 have the same conductivity type. A diffused region 3 which penetrates into the body 1 at 4 and which is of the -opposite conductivity ~ype to that of the body and of the layer, forms a ~n junction 7. m e surface of the layer 2 ~hich corresponds to non-diffused -~
regions of said layer is covered with a layer 5 of insulation material, for example, an oxide or a ni~
tridb, which leaves w~h~3~ws exposed. A contact -electr~de is deposited at 6 and another one is ; -deposited at 8 on ~he rear face of the body 1. m e~
part 4 of the diffuge~region is a cDnfin~ment zone and constitutes the active part of the dicde.
~ ~ S ~ ing m~erial for the r~nufactlre~of the diode shcwn i~ Fig. 1 is a plate of s ~ conduc-or material 11 (Fig. 2a). A large~faoe 12 of;said plate is pr:qFbred ~o reoeive an ~pitaxia1 deposit.
e deposit of the epitaxial layer 13 is carried ;;
out~tFig. 2b), the deposited~materlal having a for~ - ~
biddsn`b3n~NIdth which is largsr than ~hat of the ~ '! '' ' plate. The~surface 14 of th~ layer 13 is covered with;a layer~15 of an insulation~mat~rial which is impervious to the vapours o:E the doping products 25~ pFig. 2c~and~2d). ~ ;
A dif ~ iom~of doping irpurities is car-ried out ~hrough the W~IX~3W 16 fr~m a vapour phase ,f; , .,, .. , ,.. ., . ~ . .. , . , . , .. , ,; ,: ,, . . : , , , . - .
PHF. 74-540-which comprises said Lmpurities (Fig. 2e). The diffusion ;
`, depth should be larger than the thickness of the epi- ~ ;
taxial layer 13. The diffused region 17 deterslnLnes a junction 18. Cbntact conductors are manufactured S by depositing metal on the two large faces of the device at 19 and 20 (Fig. 2f). - , According to a particular embodiment of the method, the plate 11 is of gallium arsenide of the n type which is doped with silicon in a concentration .
of 5.1017 cm 3. The epitaxial layer 13 is of gallium ,"r, i and aluminium arsenide Gal xAlxAs, in which 0.05 ~ x C 0.4 and preferably x = 0.1, obtained by epitaxy in a li~uid solution in gallium. Said layer is doped with sulphur and tellurium in a concentration of 1017 cm 3 due to an -~
addition of said doping element in solution or in vapc~ur ~, phase. The la~er 13 has a thickness of 5 to 10 micro- -~; meters.
A ~hin layer l5 of silioon nitride is deposited on the su~rface of the layer 13 and windows are opened in ZO said layer o silicon nitride by photoet~hing according to the usu21 methods.
The diffusion is carried out in an open ampoula from a zinc source which consists o~ a zinc-gallium n~xtl~e. The tenFerature of the plate is 760~C, the zinc vapour is a dry vapour and the diffusicn duration is in the order of 2 hours, to achieve a diffusion depth which is 0.5 to 1 micrcmeter more than the thick-'s~
~3 ,. .
~s~ - 15 -.~1 ~ , .
, ~7 ~ ; ,:
.'~,, " ;"" ~ .
`~ PHF. 74-540. 3~
; ness of the epitaxial layer 13. me average concentra-tion of the diffused region is in the order of 1019 ~ ;
zinc atoms per cm3. me contact electrodes can be - manufactNred by depositing aluminium which is evapor- ;
ated in a vacuum according ~o the usual methods.
e device shcwn in Fig. 3 is an i~proved variation of the device shcwn in Fig. 1. It is manr ufactured in a substrate 31 having an epitaxial layer 32. A dif~used region 33, 34, 35 oomprises twD zones: a central zone 33, 34 the part 34 of ~;
.J ~ which forms the junction 36 is the part which is electroluminescent by injection, confinement and recombination of carriers and a shallow surface zone 35 which forms the junction 37. The zone 33, 34 ~ gives an optimum dbping concentrati~n~f~r the lumi-nance and t~e~zone 35 a dcping concentration which is o~tlmum for ccntacting by m~ans of a metal depo-sit 38. The layer 39 is a thin lccalized insulation laye~ and the layer 40 is a thin metal contact layer.
20~ It is foundi thak the junction 36 corre~pcnding to he e1eotrolrnLn~scent emission region is protec~ed ~ ;
rom po~sible large elec*r~lc currents by the junction : 37 hlving a larger surface, a less strong series ; resistance and ic~m~d in a ~aterial h=vmg a lar~er 25 ~ ~ ~ i' ~ dd=n bandwldth. ;;
In certain cases the devi oe shcwn in ~ig.
,!j';~ , ~ 16 -j . ,::: . , ';),: .. : . : !' .. ' '~,, j!,,.
:,,,, , , , -PHF. 74-540, . . .
4 shcws advantages with respect to that shcwn in Fig. 3. ~, Actu~lly it comprises a body formed from a substrate '-, 41 which is covered with a first epitaxial layer 51, ~
which ~nables on the one hand to choose ~or the kody ,~ , 41 a material of a good mechanical quality and lcw price and on the other hand for the layer 51 a -,~ , '-material of good optoelectronic quality. A second , ;~ , epitaxial layer 42 covers the first but has a dif~
ferent composition. This device comprises, like the ', ~ , preceding one, a diffused region 43, 44, 45 having tw~
zones: a central zone 43, 44 of which the part 4~ ;
forms a junction 46, forms the electroluminescent ''~'''' part and a shallow surface zone 45 forms a junction ', 47. The centlal zone 43, 44 is dop~d so as to obtain ~ ~-,' , 15 ~- an optimum electco1uminescent ef~ect~ the zone 45 is doped'so as to obt~un an opt~mlm contact possibility.
According to a variation shcwn in Fig. 5 , ' the'surface zone 52 is diffused aco~rding to an anr nular face leavi~g in the centre the'surface part '' '~
20' of the'zone S3'at the same level as the deeper part .
~,~ The'methoas o~ manufacturing devices'as ' ' shown in Figs. 3 'and 4 may camprise the same opera-tions as the'me*hod descriked with reference to 25 ~ Figs. 2a and 2f. In addition they comprise an extra : masking treatment and an extra diffusion treatment ~: T~hiCh have tD be carried out after the diffusion of :, ': .
; PHF. 74-540. ~
i ~B~4 .. ...
` the active electroluminescent region so as to realize the .. ~ . . .
oontact zone. The mainufacture of the devioe shown in Fig. 4 comprises in addition the deposition in such -; manner in two phases that the double epitaxial layer of heterogeneous composition is manufactured.
In an embodiment acoording to the struicture shown in Fig. 4 the ~ody is o~ galIium arsenide of the ~
; n-type and is doped with silicon in a concentration of ;~ -~, 5.1017 cm 3. ' : ' .. .
! 10 The first epitaxial layer~of gallium and alum~
; ~ Lnium arsenide Gal_ ~ ~ in which 0.1 < y ~ 0.2 and has been obtained by liquid el~taxy. mis layer is ,: , doped wi~ ~ulphur in`a co~c.ntratior of 5.1016 cm 3. ~`, The thickness thereof lS 20 rdcromEters. The seoond ' 15;~ epLtarial layer~is ~of galllu~ and aluminLum arsenLde in w~ c 0.2 ~ x ~ 0.4, obtair.ed by~ d :~
epitaxy. Said second layer is doped with sulphur in a concrntra~on of 5.10 cm , the thickness thereof is ~ ~
3 to 5 miczomlters. ~ ;
70` ~ ~ The cmntral di~fused r:gion is ~ped with zinc in an avmrag2 conoentration Oæ lO19 cm~3.~ ThR
dlsret2r thereo~ i8r ~or example, 100 micrometers.~
The surface zcne i8 also doped wlth zinc in a surface . I
c~ncentration 0~ 102 cm 3; ~ diameter ~ eof is, 25~ for exanplm, 200 mlcrometers.
, il, ~ ~ ... .
3~
.... ... ..
"Electroluminescent device of heterogeneous structure and method of manufacturing same".
~,,", me present invention relates to a semiconr ;~ ductor devioe of a heterogeneous structure and compris-ing an electrDluminescent diode having a body of at least one material having a first forbidden bandwidth - ' and electroluminescent properties and an epitaxial layer of a material having a larger for~idden band-width, the said kody having a p-n junction in the proximity o~ ths intexface with the said layer.
e present invention also relates to a 10 ~ method of manufacturiny said electroluminescent de-vloe.
Electroluminescent diodes are knswn having a semiconduc*or junction~which use the sorcalled "oonfin:m~ne effect" of the charge carriers. me ; 15 ~ confinem nt, in the reccmbLnation region, of the minority charge carriers which are injected in a diode having a ~n junction results frcm the presence o~ a pstential barrier which endea~Durs bD ~oroe said . ~ , ..
carrier~ back. The~potential barrier is obtained ky nanufaotDring a hetl~sxeneous structure with a layer ~;
o a material having a larger ~orbidd~n bandhldth -~
han that of t;he material of ~he bo~y on which said layer i~ deposited. Elec~rolu=~nescent devices o~
.: :
~ 2 ~ ~
;.~~ , . ' ' ;~ . :
PHF. 74-540.
9~ ~
this type are described in the Uhited States publica-tion "Proceedings of the IEEE", August 1971, E~
1263 and 1264.
For the manufacture of said devices there is deposited an epit~xial layer of a conductivity type which is opposite to that which serves as a substrate, in which the active junction proves to be ;-; foroed back into a substrate, either by diffusion in-; to the latter before the deposition of the layer, or ~ 10 by diffusion of doping Lmpuritieis in the layer durLng -'~ the epi~axial grcwth. However, said devices have no localized junction. The emission region proves to be limited oMly by measures in thie field of shape and cont-~ct, which prese~t difficulties~in~the perfornance.
;}5~ The coupling with an optical fibre does not give~sati6-faction, the coupling surface is not sufficlently flat,~
the~emissive;~surface is not readily~defined.~ In ad- -dition,~the~emitted~rad1 tio~ ~ouId~traverse a comr ti~ely thick region of the body, so of a~material 20 ~ having a small forbidd0n bendwidth, whose abrorption is not negligible.
On the other hand said devices have a junction which is at the same level as a s1de sur- ;
face or other surface of tha cryst~l and thus con~
stitNte plaoes for surface current~ having non-radia~ion re~mbinations~and a reduction of tha lu-rinLrus e~llolenoy.
.. ,,. , ~ .. , P~. 74~540. '''' ' ''.
. .
~ ~3~9~
A spPcial object of the present invention is to mitigate the said drawbacks and to provide and elec~
trolum mescent device which uses the confinenent effect ' ' of the minority carriers which are injected into a '~
diode of a heter3geneous structure and which shcw a ~; readily localized emissio.n, if necessary of a very ' ~ small surface and a large luminous efficiency. : '' Y According to the invention, the semiconduc- '' tor device having a heterogeneous structure and com~
1 10 prising an elsctroluminescent diodb having a body of .:
! : at least a material having a first forbidden band-width and having electroluminesc~nt properties and ,.
an epitaxial layer of a~mYterial having a læger '. ' : forbidden ba~dwidth, the said body havdng a ~n : . ' .15~ nctlon~in the'ploximdty of ~he interfaoe wi ~ the~ .
said layer, is chararterized'~in that, because the' said epi~ax1al layer'is~of~the'same cDnductivity ~ .:
kype as the said body, said device ccmprises flat .
regic~ ~ ich has been'diffused fr~m a surfxcx~part ;,' 20:. :: of the outer ~urface of the~said layer with a oon- .;
ductivit~ type which is opposite to that of the ., :: .
bcdy and o~ the la~er, said r~ion ex*ending from the emissive sur~ace of the device dcwn to a dep~h .; ;~
: which is~larger ~han ~he thickness o~ the said - .
layer.
The di~fus:l region of which the oonduc- ~
~',::' ~ ~ . :: :
4 - :
:1 ~: ' , i: .
i, .
'; PHF. 74-540.
. ~ .
31~9f~ ~ -tivity type is opposite to that of the body comprises in the epitaxial layer two parts: a part having a ;~'larger forbidden bimdwidth and in the body of the de- ~ ' '' vice a part having a less lar~e forbidden bandwidth.
-j 5 When ~he device is polarised in the forward direction, ' the m~nority carriers are subjected to the confmement effect m the thickness of the part having the le~s ; -'' ;!,,.; large forbidden bandwidth, they are ~orced ~ack by --` the potential barrier which forms the inter~ace ke~
;;;, 10 b~een the tw~ parts, hence a very larg~ vDlume effi~
;~ ciency. ' The device acoording~to the invention is in ; '' the'form of a flat structure the'surface of which is ''~' readily suitable for posiflocing the end of an o ~ ~
~ ~ cal fib~e beam. me actave électr~lu~inescent règion ` is diffused and the conventional methods of masking~
and~diffusion enable the'f.~nufacture of diffused regions on the'readily limited'regions, if necessi~ry J ~ ~ on the very small regions whlch facilitate the 20~ coupling to an optica1 fibre. ~' ; The e~rfaoe c~rren¢s which in~Dl~e non-radiation reoombination æe strongly reduced rela-' tive ~D those in the kncwn devices. If actually the ch~¢arteristic curve of the current is oonsidered ' 25~ as a function of the applied v~ltage in the forward direction o~ the device, it is seen that t~e ~Dltage o the surace part of the junction o~ the device ' ~ ' , " - S - ;
,,~ .
~; PHF. 74-540.
. , ~04~B~4 ~ which is present in the epit~xial layer is higher ~han ; the knee voltage of the deep part of said junction .~
which is present in the body made of a material having ., j .
a smaller forbidden bandwid~h, said seoond part of the , 5 j-mction corresponding ~o the electroluminescent .,~ , , active region. With supply vDltages exceeding the knee- voltage of the deep part, the current through the surface part may be neglected as co~pared with -that through the active part of the junction.
In a preferred e~bcdIment the diffused re-gion of the device of a canductivity type opposite to that of the body and of the epltarial layer oom~
prises several zones:~ a principal zone ~he deep part ;~ of:which is elsctDol D sscent and the oonosntra ~ n 15 ~ ~; of doping irpuritiss of which~is sd3çted~to said =ctlon, and a surface zone whi~ adjoins the prinr cipal zone ~nd of which the depth is smaller than l~ the thdckness of ths epitaxial layer and the co=ccnr tration of dcping irpurlties of which is adapted ~i$;; ~ ~ 20 ~ ~ for making~gupply cont30ts and for that reason is ;
oc~parativ~ly high.
The sur~ace~o~ theisurface zone prD~ect- ~i mg beyond that of ~he ~rincipal zone, it is pos-sible to use same fox makLng~a su~ficientl~ large 25~ surfaos oontact withDut using ~or that purpose a part of the emissive surfsoe o the principal zone.
~ ~ princlpal~zone on~the one side and the surface ~ -;3~
,i,~ ' .' , '.
~, : ~ :
PHF. 74-540.
'.
zone on the other side may have optimNm defect con-centrations without a compromise or a complicated concentration profile being necessary. Further~ore, on the one hand the part of the diode which corresponds;
to the surface zone adjoining the principal zone has a higher knee voltage than the emissi~e part of the diode and on the other hand has a lower series resist-ance due ~o the doping~ with high concentration, of the zone destined for the contact. Thus the active part of the diode is protected from tco high current strengths in the forward direction. Because the con-centration of doping impurities of the contact zone ;~
~ is higher than that of the ac*iv~ zone, the~breakdcwn !
'! voltage in the reverse direction is lower and the ,~
~;~ 15 actlve part of the diode is also protected fnom pos-; sibly oocurring reverse vDlta~es.
~1 . . , The thickness of the active region, or the region in which carriers are confin3d, taken between . i ~ . ; ; .: .
the surface of the junction and the interface be~ween ! 20 the substrate a~d the epitaxial layer, is determined as a function of the av~rage diffusion length of the minority carriers in the material of said region. The ! ~ ~ thickness of the active part should be so much lower ~ ~
¦ than ~he diffusion length that the possibiiity o~
~; ~5 radiatlng reoombina~ions in said region is maximum.
The ~hickness of the active region, taken between the 1 ~ junction and the interface preferably is between hal~
.',~, , - ..
PHF. 74-540. ~ ~ ~
8~ ~
and the hundred~h part of the average diffusion length ~ -~
of the minority carriers in the material of said ~ active region.
.. j . . .
~`i In an example of the device according to the ~ -`~ 5 inNention a substrate of gallium arsenide of the '` nrconductivit~ type oomprises an epitaxial layer of i the same conductivity type of galliumaluminium ar-21x~s, x beLng between 0~05 and 0.4 and ;
preferably beingsequal to 0.1. A localized diffuS^~ed 5~ tO region which is doped with: zinc in such mannar that it shows the E~conductivity type penetrates into~he~
layer and into the~substrate.
In~anothsr enbcdiment a device according ~ `~
to~the inventlcn comprises~a body ~oraed by~a pas~
15 ~ sive substra~e of a~natsrlal~ha:v mg~goDd nEohanical ies and ninimum~cost whi~ls~oovered with ;an epitaxisl layer of a mbkerial which can be db-posited m good~epitaxial conditions on the said sub-strat2~and which has m pYrtlcular been-chosen to be ;20~ so that~the intsrfsoe between said layer and the ep~ W layer o~ a material having a larger ~ox-bidden~;bar~width ha~ the best elsctrDnic properties and the best behaviour with respect ~o the mechanical and thllmal stressas to~whlch the devics may be sub-25~ jected d~ ing operatian. ~or example, the devica has been mQde of~a substrate o~ ~allium arsenide ha~ ng a layer o~ gallium and alumindum axsenide Gal- ~ yAs~
, .. .. .
PHF. 74-540. ~. .
38~
which is covered with a layer o~ gallium and aluminium arsenide Gal xAlyAs, in which x > y, the layer and the . .
first layer of gallium and aluminium arsenide being of the sam~e conductivity type as the substrate c~nd has a region diffused from the outer surfaoe of the epitaxial layer formLng a ~n junction of which the active flat ~ -: part is present in the said layer. Actually it is : .
kncwn that in the epitaxial conditions of the known methods an Lnterface between galli~m and aluninium ... :~ :
arsenides of different cc=}o~itions is of a better ..
quality ffhan an interface betwe~n gallium arsenide .
and gallium;c~nd aluminium ~rsenide, the deviation in composition being~of the same order in~bo~h cases.
: PurthermDre, in~applications;such as~phDtocDuplers 15 ~ or in op*icaL~teleoDmmunication the emLssive~spec~
trum of the~di ~ :according:to said last enbofiment :
on~the one~hand oorrespocds particularly readily to the transparent window of the transmission ~ . :
of the opkical fibres which are ~sually used in said ' ; .;
20 : ~ applicaticms, on the other hand 1n~D1~ss a bettér ;.
absorp~ion of the photon~ in the pbGtormDsiver o~ .- .: .
photoreceivers con~sntionally used in said applica-tions. ~
Plthcugh it is possible tD use a de~ioe 25~ aco~rding to~the irvention ~n whidh:the light rela~
tive to the epit~Yial Iayer m~mates:throLgh ~he rear face of the body of ~he device, if ae5ired by provid- .. ;
. ~ ~ : : .. . .
~: : .: ' ' -:
~: . .
PHF. 74-540.
,. ' , .
~ 4~B94 ` - ~
~ ing lccally a reduction of the thickness of the body, ~ it is recommendable to use it in such nanner that the light emanates from the outer surface of the epit~xial ~? layer beoause the absorption in said enission direction ~t . 5 is miDimum.
;l m e present invention also relates to a methcai .,j , .
:.~ of nanufacturing a device as described above.
;1 . According to the Lnvention, the method of manr ufacturing an electrolr~dnescent semiconductor device of a heterogeneous structure, aco~rding to which an ~ ~-epitaxial layer of a semiconductor material of a first forbidden bandwidth lS deposited on a body of a rKterial having a ~maller forbidden bandAidthi in whioh :
a E~n junction is formed in the said device near the 15~ interE~oe bKt~een said latter and the deposited~layèr, ~ -'~? ~ : is dharactKrized in~ha~.t~e said epitaiial layer i5 '. ' ' .
deposited with:a doping which gives it the same conr ductivity type as the~said laye~r and that after~the epitaxial deposition~a doping impurity is diff~ed 20~: ~ron a local ~urface on t~ie outer surface of the said layer which gives it the opposite oonductivity type dcwn to : a depth which is slightly larger tha~ the thickness of the ::.
` 9aid layer. : ..
. . Because the epitaxial layer is o~ the sa~e 25~ ccndh~tivi~y type~as the bcdy on which it is de- .-.
j; : ., ~! .~ - . .
-- .
'. i ~ ~ ' ' ' ; ',~ ~ : ' ':
'.~/ ~:-~: ;. "'' '. , ,' ' ... ', ", . .'"i,,., ' ', , ' . : ' ', ' ' '' ,' , . " ,, ' : .
PHF. 7q-540. ~
38~
posited, no diffusion occurs in which the conducti-vity type of the bcdy in the proximity of the inter-faoe can invert, neither during the deposition nor thereafter. It is possible to determine an optimum junction aepth without being dependent on the condi-, tions in which the epita~y is carried out: the !
junction depth is determined only by the conditions - -'! of the fm al diffusion and especially of the duration ~, .
;, of said operation.
Ihe diffusion from the Æ faoe can easily , be localized by the masking me~hods conventionally used in the m~nu~acture of semicondhcbor devioe s of .~ .
the flat type. With this n#thod very small junction surfaces can be delimited, for exdmple, with a 15 ~ diameter in the order of a few micrcmeters. me :
method er~hles-the`manufa ~ e of mosaics of a~y oon-figuration and di~ensions coeF3title with available semiconductor plates. .
Asoordin~ to a preferred enbodiment of the 20 ~ methcd acoordLng to ~he`invantion the epitaxial de-po~ n of the layer of a material havin~ a larger ~ ;
forbidden ban~width i9 carried out, a~ter which a ma~3k of a d~nse ma ~ rial is manufac~red on said layer and a doping impurity is diffused through the -25 ~ ~ a~pertur2s of said mask for the`necessary time, which inpurity c~n reach and~pass the interface between ` ;
the depo9ited~ layer and the body which has served .,.
~ PHF. 74-540. ~i as a substrate. For e~ample, when the bcdy is of n-type gallium arsenide, an epitaxial layer is depc~
sited of gallium and aluminium arsenide of the n-type, a masX of silicon nitride is manufactured by deposi-S tion and photoe~hing and zinc is dif~used through the aFertures of the mask for such a lcng period of time that a concentratio~ is obtained which gives the material the ~type dcwn to a depth which is larger than the thickness of the epitaxial layer.
A second diffusion of a short duration is pr~¢erably carried out which gives a maximum surface ..... ..
conoentration and a mLnimum junction depth acoording -to~a surface which pLo~ects far beyond the pre~eding diffusion surface, the extra sur~aoe being destined tD receive oontact me~ns in t~ ~o~m of a localized ~ ~ -me*al deposit. The~seo~ difusion is preferably nade with the same dcpdng i~purity as the first diffusion and by neans of a mask which is obtained, f~r example, by deposition and photoetching.
0 ~ me seoond diffusion may either ocver the first diffusion 70ne entirely or relat~ only to an annular Æ face or only a surface adjoining that of ffhe first dif~usion in such manner that the radiation abrcrption mmi ted du~t~ the central zone present 5~ ~ ~ abcve t~le emi aion regicn is reduced.
The ir~uentian may be u~ed for the m,~nufac-ture of eleotro1umincsoent devices, ~or example, r: ~ ~:
) ' ~ . ' 7 ~
~ 12 -s~
~:
PHF 74,540 . . .
diodes, destined to be coupled to photosensitive de~ -vices, in particular by the channel of optical fibres.
The devices according to the invention are preferred for uses in telemetry and optical telecommunicat;on, especially by means of optical multimode fibres.
The invention will be described in greater detail with reference to the accompanying drawings.
Fig. l is a diagrammatic cross-sectional view of a first embodiment of a diode according to -the invention.
':! Fig. 2a to 2f show the various stages of . ' . .. .
, the manufacture of the diode shown in Fig. l. - , Fig. 3 is a diagrammatic cross-sec~ional ~ view of another embodiment of a diode according to ;3~ 15 the invention. :
: .
~ Fig. 4 is a diagrammatic cross-sectional ~ ~ ~
, :~ : ; . ,.- . . .
view of a th1rd embodiment of a diode according to the invention.
Fig. 5 ~is a diagrammatic cross-sectional 20 ~ ~view of~a fourth embodiment of a d10de according to ~ ;
the invent10n.
The diagrammatic cross-sect~onal v~ew of F-3g. 1 shows a d30de which is manufactured accord3ng I to the method of the invention and which comprises a' ~ ;;
25 ~ sem~3conductor body l wh~3ch is covered dn one of the ; surfaces thereof with a layer 2 of another semicon ; ductor materia1 having a larger forbidden bandw~dth ; than the material of the body l. The body 1 and the 3~ ~ layer 2 have a crystal latt~,3ce of the same type and ~3~ 30 have constants the values o~ which are close together, ;,3~
l3 .,.
't .. .. ... . . . . . .... ... .. .. ... . . . . . . . .. . . .
PHF. 74-540.
the lattice of figure 2 elongating that of figure 1.
The materials of the body 1 and of the layer 2 have the same conductivity type. A diffused region 3 which penetrates into the body 1 at 4 and which is of the -opposite conductivity ~ype to that of the body and of the layer, forms a ~n junction 7. m e surface of the layer 2 ~hich corresponds to non-diffused -~
regions of said layer is covered with a layer 5 of insulation material, for example, an oxide or a ni~
tridb, which leaves w~h~3~ws exposed. A contact -electr~de is deposited at 6 and another one is ; -deposited at 8 on ~he rear face of the body 1. m e~
part 4 of the diffuge~region is a cDnfin~ment zone and constitutes the active part of the dicde.
~ ~ S ~ ing m~erial for the r~nufactlre~of the diode shcwn i~ Fig. 1 is a plate of s ~ conduc-or material 11 (Fig. 2a). A large~faoe 12 of;said plate is pr:qFbred ~o reoeive an ~pitaxia1 deposit.
e deposit of the epitaxial layer 13 is carried ;;
out~tFig. 2b), the deposited~materlal having a for~ - ~
biddsn`b3n~NIdth which is largsr than ~hat of the ~ '! '' ' plate. The~surface 14 of th~ layer 13 is covered with;a layer~15 of an insulation~mat~rial which is impervious to the vapours o:E the doping products 25~ pFig. 2c~and~2d). ~ ;
A dif ~ iom~of doping irpurities is car-ried out ~hrough the W~IX~3W 16 fr~m a vapour phase ,f; , .,, .. , ,.. ., . ~ . .. , . , . , .. , ,; ,: ,, . . : , , , . - .
PHF. 74-540-which comprises said Lmpurities (Fig. 2e). The diffusion ;
`, depth should be larger than the thickness of the epi- ~ ;
taxial layer 13. The diffused region 17 deterslnLnes a junction 18. Cbntact conductors are manufactured S by depositing metal on the two large faces of the device at 19 and 20 (Fig. 2f). - , According to a particular embodiment of the method, the plate 11 is of gallium arsenide of the n type which is doped with silicon in a concentration .
of 5.1017 cm 3. The epitaxial layer 13 is of gallium ,"r, i and aluminium arsenide Gal xAlxAs, in which 0.05 ~ x C 0.4 and preferably x = 0.1, obtained by epitaxy in a li~uid solution in gallium. Said layer is doped with sulphur and tellurium in a concentration of 1017 cm 3 due to an -~
addition of said doping element in solution or in vapc~ur ~, phase. The la~er 13 has a thickness of 5 to 10 micro- -~; meters.
A ~hin layer l5 of silioon nitride is deposited on the su~rface of the layer 13 and windows are opened in ZO said layer o silicon nitride by photoet~hing according to the usu21 methods.
The diffusion is carried out in an open ampoula from a zinc source which consists o~ a zinc-gallium n~xtl~e. The tenFerature of the plate is 760~C, the zinc vapour is a dry vapour and the diffusicn duration is in the order of 2 hours, to achieve a diffusion depth which is 0.5 to 1 micrcmeter more than the thick-'s~
~3 ,. .
~s~ - 15 -.~1 ~ , .
, ~7 ~ ; ,:
.'~,, " ;"" ~ .
`~ PHF. 74-540. 3~
; ness of the epitaxial layer 13. me average concentra-tion of the diffused region is in the order of 1019 ~ ;
zinc atoms per cm3. me contact electrodes can be - manufactNred by depositing aluminium which is evapor- ;
ated in a vacuum according ~o the usual methods.
e device shcwn in Fig. 3 is an i~proved variation of the device shcwn in Fig. 1. It is manr ufactured in a substrate 31 having an epitaxial layer 32. A dif~used region 33, 34, 35 oomprises twD zones: a central zone 33, 34 the part 34 of ~;
.J ~ which forms the junction 36 is the part which is electroluminescent by injection, confinement and recombination of carriers and a shallow surface zone 35 which forms the junction 37. The zone 33, 34 ~ gives an optimum dbping concentrati~n~f~r the lumi-nance and t~e~zone 35 a dcping concentration which is o~tlmum for ccntacting by m~ans of a metal depo-sit 38. The layer 39 is a thin lccalized insulation laye~ and the layer 40 is a thin metal contact layer.
20~ It is foundi thak the junction 36 corre~pcnding to he e1eotrolrnLn~scent emission region is protec~ed ~ ;
rom po~sible large elec*r~lc currents by the junction : 37 hlving a larger surface, a less strong series ; resistance and ic~m~d in a ~aterial h=vmg a lar~er 25 ~ ~ ~ i' ~ dd=n bandwldth. ;;
In certain cases the devi oe shcwn in ~ig.
,!j';~ , ~ 16 -j . ,::: . , ';),: .. : . : !' .. ' '~,, j!,,.
:,,,, , , , -PHF. 74-540, . . .
4 shcws advantages with respect to that shcwn in Fig. 3. ~, Actu~lly it comprises a body formed from a substrate '-, 41 which is covered with a first epitaxial layer 51, ~
which ~nables on the one hand to choose ~or the kody ,~ , 41 a material of a good mechanical quality and lcw price and on the other hand for the layer 51 a -,~ , '-material of good optoelectronic quality. A second , ;~ , epitaxial layer 42 covers the first but has a dif~
ferent composition. This device comprises, like the ', ~ , preceding one, a diffused region 43, 44, 45 having tw~
zones: a central zone 43, 44 of which the part 4~ ;
forms a junction 46, forms the electroluminescent ''~'''' part and a shallow surface zone 45 forms a junction ', 47. The centlal zone 43, 44 is dop~d so as to obtain ~ ~-,' , 15 ~- an optimum electco1uminescent ef~ect~ the zone 45 is doped'so as to obt~un an opt~mlm contact possibility.
According to a variation shcwn in Fig. 5 , ' the'surface zone 52 is diffused aco~rding to an anr nular face leavi~g in the centre the'surface part '' '~
20' of the'zone S3'at the same level as the deeper part .
~,~ The'methoas o~ manufacturing devices'as ' ' shown in Figs. 3 'and 4 may camprise the same opera-tions as the'me*hod descriked with reference to 25 ~ Figs. 2a and 2f. In addition they comprise an extra : masking treatment and an extra diffusion treatment ~: T~hiCh have tD be carried out after the diffusion of :, ': .
; PHF. 74-540. ~
i ~B~4 .. ...
` the active electroluminescent region so as to realize the .. ~ . . .
oontact zone. The mainufacture of the devioe shown in Fig. 4 comprises in addition the deposition in such -; manner in two phases that the double epitaxial layer of heterogeneous composition is manufactured.
In an embodiment acoording to the struicture shown in Fig. 4 the ~ody is o~ galIium arsenide of the ~
; n-type and is doped with silicon in a concentration of ;~ -~, 5.1017 cm 3. ' : ' .. .
! 10 The first epitaxial layer~of gallium and alum~
; ~ Lnium arsenide Gal_ ~ ~ in which 0.1 < y ~ 0.2 and has been obtained by liquid el~taxy. mis layer is ,: , doped wi~ ~ulphur in`a co~c.ntratior of 5.1016 cm 3. ~`, The thickness thereof lS 20 rdcromEters. The seoond ' 15;~ epLtarial layer~is ~of galllu~ and aluminLum arsenLde in w~ c 0.2 ~ x ~ 0.4, obtair.ed by~ d :~
epitaxy. Said second layer is doped with sulphur in a concrntra~on of 5.10 cm , the thickness thereof is ~ ~
3 to 5 miczomlters. ~ ;
70` ~ ~ The cmntral di~fused r:gion is ~ped with zinc in an avmrag2 conoentration Oæ lO19 cm~3.~ ThR
dlsret2r thereo~ i8r ~or example, 100 micrometers.~
The surface zcne i8 also doped wlth zinc in a surface . I
c~ncentration 0~ 102 cm 3; ~ diameter ~ eof is, 25~ for exanplm, 200 mlcrometers.
, il, ~ ~ ... .
Claims (7)
1. An electroluminescent semiconductor device comprising:
a body of first semiconductor material having a major surface;
a flat zone, nested within said body, adjoining a portion of said major surface, and being, otherwise, wholly surrounded by said body, said zone having a conductivity type opposite to the con-ductivity type of said body and forming a p-n homojunction there-with, said zone having electroluminescent properties; and an epitaxial layer of second semiconductor material having a first region covering said flat zone with a conductivity type the same as said zone and a second region surrounding said first region from said major surface of said body to a major surface of said layer, said second region having a conductivity type the same as said body said second semiconductor material having a forbidden bandwidth greater than the forbidden bandwidth of said first semiconductor material so that confinement effects occur within said flat zone and electroluminescent emission may occur therefrom through said first region of said epitaxial layer and an insulating layer on the epitaxial layer covering said second region and the pn-junction where it reaches the surface of the epitaxial layer.
a body of first semiconductor material having a major surface;
a flat zone, nested within said body, adjoining a portion of said major surface, and being, otherwise, wholly surrounded by said body, said zone having a conductivity type opposite to the con-ductivity type of said body and forming a p-n homojunction there-with, said zone having electroluminescent properties; and an epitaxial layer of second semiconductor material having a first region covering said flat zone with a conductivity type the same as said zone and a second region surrounding said first region from said major surface of said body to a major surface of said layer, said second region having a conductivity type the same as said body said second semiconductor material having a forbidden bandwidth greater than the forbidden bandwidth of said first semiconductor material so that confinement effects occur within said flat zone and electroluminescent emission may occur therefrom through said first region of said epitaxial layer and an insulating layer on the epitaxial layer covering said second region and the pn-junction where it reaches the surface of the epitaxial layer.
2. A device as claimed in Claim 1, characterized in that at least the first region of the epitaxial layer contains a surface zone having a high doping which is destined for contact possibilities.
3. A device as claimed in Claim 1, characterized in that the thickness of the active region for confining carriers, taken between the surface of the junction and the interface between the body and the epitaxial layer, is smaller than the average diffusion length of the minority carriers in the material of said active region.
4. A device as claimed in Claim 3, characterized in that the said thickness of the active region is present between half and the hundredth part of the average diffusion length of the minority carriers.
5. A device as claimed in Claim 1, characterized in that the body is formed from a passive substrate which is covered with a second epitaxial layer of the same conductivity type in which the electroluminescent zone is present, the material of the epitaxial flat layer having a larger forbidden bandwidth than the material of the second layer.
6. A device as claimed in Claim 1, characterized in that the emissive surface is a flat outer surface of the epitaxial layer, the said emissive surface and the surface of the body present on the side remote from the said layer com-prising a contact means in the form of a thin metal layer.
7. A device as claimed in Claim 5, characterized in that the body is of n-type gallium arsenide, the epitaxial layer is of gallium and aluminium arsenide Ga1-xAlxAs, in which 0.05 < x < 0.4, while the said second epitaxial layer is of gallium and aluminium arsenide Ga1-yAlyAs, in which y < x.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7416054A FR2270753B1 (en) | 1974-05-09 | 1974-05-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043894A true CA1043894A (en) | 1978-12-05 |
Family
ID=9138632
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA226,180A Expired CA1043894A (en) | 1974-05-09 | 1975-05-02 | Electroluminescent device of heterogeneous structure and method of manufacturing same |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS50159688A (en) |
| CA (1) | CA1043894A (en) |
| DE (1) | DE2520061C2 (en) |
| FR (1) | FR2270753B1 (en) |
| GB (1) | GB1503678A (en) |
| IT (1) | IT1037913B (en) |
| NL (1) | NL7505276A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2376513A1 (en) * | 1976-12-31 | 1978-07-28 | Radiotechnique Compelec | SEMICONDUCTOR DEVICE EQUIPPED WITH A PROTECTIVE FILM |
| GB1569369A (en) * | 1977-04-01 | 1980-06-11 | Standard Telephones Cables Ltd | Injection lasers |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS502235B1 (en) * | 1970-09-07 | 1975-01-24 | ||
| FR2119176A5 (en) * | 1970-12-23 | 1972-08-04 | Radiotechnique Compelec | Monolithic semiconductor body - comprising binary cpd substrate and active layer of a ternary cpd |
-
1974
- 1974-05-09 FR FR7416054A patent/FR2270753B1/fr not_active Expired
-
1975
- 1975-05-02 CA CA226,180A patent/CA1043894A/en not_active Expired
- 1975-05-06 IT IT23083/75A patent/IT1037913B/en active
- 1975-05-06 NL NL7505276A patent/NL7505276A/en not_active Application Discontinuation
- 1975-05-06 DE DE2520061A patent/DE2520061C2/en not_active Expired
- 1975-05-06 GB GB18958/75A patent/GB1503678A/en not_active Expired
- 1975-05-08 JP JP5535475A patent/JPS50159688A/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IT1037913B (en) | 1979-11-20 |
| FR2270753B1 (en) | 1977-10-21 |
| DE2520061A1 (en) | 1975-11-20 |
| NL7505276A (en) | 1975-11-11 |
| GB1503678A (en) | 1978-03-15 |
| FR2270753A1 (en) | 1975-12-05 |
| DE2520061C2 (en) | 1983-12-08 |
| JPS50159688A (en) | 1975-12-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4651187A (en) | Avalanche photodiode | |
| US4904608A (en) | Pin photodiode having a low leakage current | |
| JP3156851B2 (en) | Heterojunction energy gradient structure | |
| DE2631744C2 (en) | ||
| US5157473A (en) | Avalanche photodiode having guard ring | |
| EP0163546B1 (en) | Process for fabricating an avalanche photodiode and an avalanche photodiode thus-obtained | |
| US4755485A (en) | Method of making light-emitting diodes | |
| KR910009357B1 (en) | Semiconductor device photo diode | |
| DE2756426A1 (en) | SEMICONDUCTOR ARRANGEMENT WITH PASSIVATION LAYER | |
| Liao et al. | Visible electroluminescence from Si+-implanted SiO2 films thermally grown on crystalline Si | |
| DE2915888C2 (en) | ||
| CA1155968A (en) | Zener diode | |
| Michel et al. | Light Emission from Reverse Biased GaAs and InP p‐n Junctions | |
| US4063276A (en) | Semiconductor photoelectron emission device | |
| CA1043894A (en) | Electroluminescent device of heterogeneous structure and method of manufacturing same | |
| DE2534945A1 (en) | LIGHT DIODE AND METHOD OF MANUFACTURING IT | |
| US4935795A (en) | Avalanche photodiode with uniform avalanche multiplication | |
| EP0214485B1 (en) | Asymmetric thyristor and method of making the same | |
| CA1111571A (en) | Semiconductor element capable of withstanding high voltage and method of manufacturing the same | |
| US5107311A (en) | Semiconductor light-emitting device | |
| CA1261045A (en) | Avalanche photodiode | |
| US4077819A (en) | Technique for passivating semiconductor devices | |
| KR960004594B1 (en) | Infrared ray light detecting sensor | |
| US4816890A (en) | Optoelectronic device | |
| Gu et al. | MIS electroluminescent diodes in ZnTe prepared by Al vapor diffusion |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |
Effective date: 19951205 |