Note: Descriptions are shown in the official language in which they were submitted.
RELATED APPLICATIONS
. .
This applica-tion is related to the following co-pending
applications, assigned to the same assignee as this applica-
tion. Canadian Patent Application entitled CATENATED PHOS-
PHORUS MATERIALS, THEIR PREPARATION AND USE, AND SEMICONDUC-
T~RAND OTHER DEVICES E~PLOYING THEM, Serial No. 418,657, filed
December 29, 1982; GRAPHITE INTERCALATED ALKALI METAL VAPOR
SOURCES, filed concurrently; SPUTTERED SEMICONDUCTING FILMS
OF CATENATED PHOSPHORUS MATERIAL AND DEVICES FORMED THEREFROM,
filed concurrently; and, LIQUID PHASE GROWTH OF CRYSTALLINE
POLYPHOSPHIDE, filed concurrently,also, the applications filed
herewith of David G. Brock and John A. Baumann for THER~L
CRACKERS FOR FO~ING PNICTIDE FILMS IN HIGH VACUUM PROCESSES;
Mark A. Kuck and Susan W. Gersten for CONTINUOUS PNICTIDE
SOURCE AND DELIVERY SYSTEM FOR FILM DEPOSITION, PARTICULARLY
BY CHEMICAL VAPOR DEPOSITION; Mark A. Kuck and Susan W. Gersten
for METHOD OF PREPARING HIGH PURITY WHITE PHOSPHORUS; Robert
Parry, John A. Baumann and Rozalie Schachter for PNICTIDE
TRAP FOR VACUUM SYSTEMS; and, Mark A. Kuck, Susan W. Gersten,
John A. Baumann and Paul M. Raccah for HIGH VACUUM DEPOSITION
PROCESSES EMPLOYING A CONTINUOUS PNICTIDE DELIVERY SYSTEM.
.~ - 2 ~ ) 0 7 . 1
C. 7244 & C. 7473
TECHN I CAL F' I ELD
This application relates to the passivation and insu-
lation of III-V devices with pnictides, particularly amor-
phous pnictides having a layer-like puckered sheet-like
structure; compound, intermetallic semiconductors, particu-
larly III~V semiconductors; to pnictide and polypnictides,
particularly phosphorus and polyphosphides; to MIS and
metal-semiconductor (Schottky) devices, particularly MISFETS
and MFSFETS; to light absorbing diodes, particularly P-I-N
and avalanche detector diodes, solar cells, and photo
cathodes; and to light emitting diodes, and lasers.
9~ !
_3~ 110.007.1
C.72~ ~ C.7~73
BACKGROUND ART
III-V semiconductors have desirable pxoperties of high-
er carrier mobility than silicon. They have been
successfully employed in metal semiconductor (Schottky)
devices, but have not been commercially employed in the more
widely useful metal-insula-tor-semiconductor (MIS) devices.
A reason for this is that the native oxides o-F the III-V
materials do no-t form thermodynamically stable layers there-
on in the way that silicon dioxide layers can be formed on
silicon to form MIS devices. Silicon oxynitride and Si3N4
have been used as an insulating layer on III-V materials
with limited success.
The passivation of III-V semiconductors has been a
problem for the same reasons.
Thus it is highly desirable to find a material, and a
means o producing it, which readily forms an insulating and
passivating layer on III-V materials and thus provide the
basis for the formation of MIS and Schottky devices,
particularly MISFETS and MESFETS.
Similarly, it is desirable to reduce the surface com-
ponent of currents in III-V opto-electronic devices by
passivating the surface thereof.
It is also desirable to decrease the carrier recombi-
nation velocity at the surface of III-V opto-electronic
devices.
24~8~ 110.007.1
C. 724~ ~ C. 7~73
DISCLOSURE OF THE INVENTION
We have discovered that insu~ating, passivating and
surface recombination velocity reducing pnictide rich layers
can be formed on III-V semiconductor suhstrates by various
methods that pnictide rich layers may be formed on any sub-
strate. These include vacuum co-evaporation, sputtering,
chemical vapor deposition, two-source vapor transport,
deposition from a liquid melt and molecular beam deposition
which produces the best results.
In particular, we have deposited an alkali metal poly-
phosphide layer, namely KP15, on gallium arsenide, and
gallium phosphide, indium phosphide and Si. We have also
deposited insulating and passivating layers of high x alkali
metal polyphosphides having the formula MPX where x is
greater than 15 on these materials. For all practical
purposes, such very high x materials are elemental
phosphorus.
We have also deposited elemental phosphorus layers on
substrates of gallium arsenide, gallium phosphide and indium
phosphide using these same processes. We -fully expect that
other III-V semiconductors may also be used as substrates.
We contemplate that other high pnictide polypnictides,
particularly alkali metal polypnictides and other elemental
pnictides comprising Group V atoms will also form useful
insulating layers and semiconductors comprising a pnictide.
These pnictide materials are insulators or very high
resistivity semiconductors, good film formers, and the
pnictides, being group V materials, provide chemical
continuity , matching order, and adhesion to the group V
atoms of the group V containing semiconductors.
The insulating layers of our invention have a resistiv-
ity of greater than 10 10 ohm-cm. which is greater than the
resistivity of the III-V materials.
We have successfully added another Si3N9 layer on top
of a pnictide layer of III-V materials to provide a higher
breakdown voltage.
_5_ ~ 11U.007.1
C.724~ h C.7fi73
The amorphous layers we employ have a 1ocal order not
found before in amorphous pnictide films deposited on a
III-V substrate. This is a layer-like puckered sheet-like
structure similar to black phosphorus. This structure
apparently forms at lo~l effective energies at the surface
during the deposition. Thus, in vacuum evaporation and
molecular beam deposi-tion when the surface is kept below
approximatelv 200C this new layer-like puckered shee-t
amorphous polyphosphide material forms. Similarly, at low
energieC, and at ternperatures below appro~.imately 300C the
same material forms in a sputterer. The material is formed
by deposition from excess phosphorus supplied as P4 vapor,
which is crac~.ed to P2 vapor by a heated cracker in the case
of vacuum deposition and molecular beam deposition and is
cracked by the plasma in a sputterer.
The surface layers according to our invention reduce
the density of surface states, allows modulation of the
depletion layer, reduce the surface barrier, increase the
surface electron concentration, and increase the
photoluminescence intensity and decrease the surface carrier
recombination velocity.
The pnictide layers according to the invention may be
used to insulate and passivate MIS and Schottky devices,
particularly MISFETS and MESFETS, to reduce the surface
current between different layers in III-V devices such as
the dark current in reverse biased light detectiny diodes,
particularly P-I-N and avalanche diodes, and to increase the
efficiency of liyht emitting and light collecting opto-
electronic devices, particularly solar cells, photocathodes,
liyht emittiny diodes, lasers, and photo detectors.
- 5a -
The invention provides a semiconductor devlce
comprising a pnictide having a pnictide-rich layer
deposited thereon, the pnictide-rich layer comprisiny
either an elemental pnictide or the polypnictide MPX where
M is an alkali metal, P is a pnictide and x ranges from 15
through infinity.
The invention further provides a method of
insulating a semiconductor device comprising deposi-ting
thereon a pnictide-rich insulating layer as described
above.
. .
-6~ 110.007.1
C.72'14 ~ C.7473
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide
insulating layers for semiconductors comprising pnictides.
Another object of the invention is to provide
passivating layers for semiconductors comprising pnictides.
A further object of the invention is to provide a new
form of amorphous pnictides.
Still another object of the invention is to provide
improved MIS and Schottky devices; including MISFETS and MESFETS.
A still further object of the invention is to provide
improved opto-electronic devices, including light emitting
and light collecting devices such as P~I-N and avalanche
diodes, solar cells, photocathodes, light emitting diodes
and lasers.
The invention accordingly comprises the several steps
and the relation of one or more of such steps with respect
to each of the others, and the articles possessing the
features, properties, and the relation of elements, which
are exemplified in the following detailed disclosure. The
scope of the invention is indicated in the claims.
~ C.7244 ~ C 7~i3
BRIEF DESCXIPTION OF THE DRAWINGS
For a fuller understanding o~ the nature and ~bjects of
the invention reference should be made to the following
detailed description taken in connection with the
ac^ompanying drawings in which: .
Figure 1 is a plot Rama~ spectra of films grown at
different substrate temperatures;
Figure 2 is a comparison of the Raman spectra of the
film grown at low temperature with the theoretical
prediction for a puckered sheet layer-like structure;
Figure 3 is a plot of normali~ed capacitance versus
voltage for indium phosphide having a insulating layer
thereon according to the present invention;
Figure ~ is a plot of the density of surface states
versus energy for various possible insulating and
passivating layers on indium phosphide accordiny to the
present invention;
Figure 5 is a plot o~ normalized capacitance versus
voltage for gallium arsenide having a layer deposited
thereon according to the present invention;
Figure 6 is a comparison of the intensities of the
Raman spectra of gallium arsenide with and without a film
according to the present invention deposited thereon;
Figure 7 is a comparison of the line shape of the
photoluminescence of gallium arsenide with and without a
film according to the present invention deposited thereon;
Figure 8 is a comparison of the intensities of the
photoluminescence of gallium arsenide with and without a
film according to the present invention deposited thereon;
Figure 9 is a diagrammatic cross section of a MISFET
according to the present invention;
Figure 10 is a diagrammatic cross section of a MESFET
according to the present inventioni
Figure 11 is a diagrammatic cross section of a MISFET
according to the present invention;
110.007.1
C.7~44 ~ C~7~73
Figure 12 is a diagrammatic cross section of a photo
detecting diode according to the present invention;
Fiaure 13 is a diagrammatic cross section of another
photo detecting diode according to the present invention;
Figure 14 is a diagrammatic cross section of a light
collecting device according to the present invention; and
Figure 15 is a diagrammatic cross section of a light
emitting device according to the present invention.
The same reference characters refer to the same
elements throughout the several views of the drawinys.
-9- lln . 007.1
C.7244 & C.7473
~EST MODE FOR CARR~ING O~T THE INVENTION
We have found that pnictides films grown at relatively
low temperatures, below 300C at low powers in sputtering
an~ below 200~C in vacuum evaporation and molecular beam
deposition, have a puc~;ered sheet-like, layer-like, struc-
ture similar to black phosphorus. These amorphous films are
deposited from phosphorus in the form of P4 vapor which is
cracked by the plasma in sputtering and by a heated cracke~
in vacuum evaporation and molecular beam deposition.
~ eference should be had to the above-identi~ied co-
pending applications VACUUM DEPOSITION PROCESSES EMPLOYING
A CONTINUOUS PNICTIDE DELIVERY SYSTFM, PARTICULARLY SPUTTER-
ING, wherein accurate metered amounts of Pnictide4 species
are delivered via an Argon carrier gas into an evacuated
sputtering deposition chamber. The pnictide is maintained at
a high temperature in a tall column by means of a constant
oil bath and an inert gas, such as Argon, and passed through
the column of pnictide and the Pnictide4 enriched carrier
gas is delivered to the vacuum chamber. Films of pnictide,
polypnictide and othex pnictide compounds may be deposited
for semiconduc-tor, thin film transistors and other applica-
tions, HIGH VACUUM DEPOSITION PROCESSES EMPLOYING A CONTIN-
UOUS PNICTIDE DELIVEP~Y SY5TEM, wherein accurate metered
amounts of Pnictide4 species are delivered via an Argon
carrier gas into a high vacuum deposition chamber, which
may be,for example, vacuum deposition apparatus or molecular
beam epitaxy apparatus. The pressure is maintained below
10 3 Torr. The pnictide is maintained at a high temperature
in a tall column by means of a constan-t temperature oil bath
or tube ~urnace and the inert gas, such as Argon, is passed
through the column of pnictide and the Pnictide~ enriched
carrier gas is delivered to the vacuum chamber. This pnic-
tide feed system may be used to supply Pnictide~ species
as a control leak to various high vacuum film deposition
processes. THERMAL CRACKERS FOR FORMING PNICTIDE FILMS IN
- 9a -
HIGH VACUUM PROCESSES, wherein, fine quality pnictide films
are produced in a high vacuum by evaporation and molecular
beam epitaxy. In vacuum evaporation heated tungsten wire
crackers are provided above the phosphorus boat and below
the substrates. Amorphous pure phosphorus shiny red films
have been deposited on glass, metalized glass, GaP, InP,
GaAs and exhibit an optical edge at 2.0 eV. Films of KPX
where x is equal to 15 or greater than 15 are produced by
utilizing a second baffled boat source containing the
potassium graphite intercalate, KC8. Better quality films
are formed in molecular beam epitaxy apparatus where a
thermal cracker is located between the exit end of the
pnictide collimator and the substrates.
We have found that pure phosphorus films, and presum-
ably films of other pure pnictides, form the best insulation
and passivating layers on III-V materials. This is because
the pnictide layer is capable of matching the pnictides
within the III-V semiconductors. Polypnictides, particular-
ly MPX where M is an alkali metal and x ranges from 15 to
infinity may also be used. We believe that our insulating
and passivating films may be used on any compound or inter-
metallic semiconductor comprising a pnictide. We have de-
posited such films on the ~ 100~ and CllO~ of
various III-V s~miconductors.
The best results to date have been with phosphorus
films having a typical thickness of approximately 400A
deposit~d on III~V semiconductors solely from a phosphorus
source by molecular beam deposition.
Figure 1 is a comparison of the Raman spectra of poly-
phosphide films grown by vacuum evaporation (250C) and
molecular beam deposition (20C). The solid line spectrum,
when the substrate is at 250~C, is typical spectrum similar
to amorphous red phosphorus indicating a local order com-
prising parallel pentagonal tubes. The dotted line spectrum
of the film formed at approximately 20~C indicates a much
-10- ~J~ 110.007.1
C.724~ & C.7~73
different local order. Films produced by sputtering at
temperatures less than that or equal to approximately 300C
have the same Raman spectra as the 20~C molecular beam depo-
sition results sho~n in Figure 1.
Figure 2 is a comparison of the Raman spectrum of film
grown at a substrate temperature of 20C, shown in do~ted
lines, with a theoretical prediction of the spectrum of a
puckered sheet-like, layer-like, structure simliar to black
phosphorus.
We conclude that the local order of these films is the
amorphous counterpart of the puckered layer-like, sheet-
like, crystalline structure of black phosphorus.
This local order is simpler than that of the films
described in the above-identified previously filed co-
pending applications which have a local order comprising
pentagonal tubes. We have found that the energy band gap of
this new form of amorphous phosphorus according to our in-
vention is approximately 1.7eV versus a bandgap of approxi-
mately 2.0eV for amorphous red phosphorus. We have not
detected any photoconductivity or photoluminescence from
phosphorus films of this type. The films are shiny, hard
and stable.
We concluded that these films would he good candidates
for insulating and passivating layers for III-V materials.
Results of Electrical Measurements of Phosphorus Thin
Films Grown On Indium Phosphide and Galium Arsenide
Amorphous thin films of phosphorus of a typical thick-
ness of 400A have been grown by molecular beam deposition on
the ~100~ surface of InP and the ~00~ surface of GaAs, the
substrates being maintained at room temperatuxe, approxi-
mately 23~C.
The InP is specified by -the manuEacturer to contain
2 x 1015 free electrons per cubic centimeter; the galli~m
arsenide to contain 2 x 1016 free electrons per cubic
centimeter.
t~
o . on7 . l
C.724~ & C.7~73
Figure 3 is a comparison of the theoretical Isolid
line) and experi~ental (dotted line) data plots of
normalized capacitance versus voltage for an ~IS structure
on InP. The solid line (theoretical) curve is computed for
the case of ideal conditions, namely a perfect insulatio
and a negligibly small density of surface states.
Excellent agreement between experiment and theory is
shown in these high frequency C-V curves. This indicates
that a low density of surface states has been achieved by
the phosphorus layer on the InP and that the phosphorus
layer allows modulation of the depletion layer.
The density of the surface states can be calculated by
Terman's method. Figure ~ is a comparison of the density of
surface states for passivation with SiO2, ~1203, P3~5, and P
(our phosphorus layer) and it can be seen tha~ we have
achieved the lowest density of surface states reported on
III-V materials.
EC in Figure ~ is the energy of the conduction band and
EV is the energy of the valence band.
~ igure 5 is such a comparison for GaAs. It will be
seen that the depletion laver has been modulated but that
the density of surface states has not been reduced as
much as in the case of InP.
Passivation Studies of Phosphorus Lavers on GaAs
Fi~ure ~ is a comparison of the intensities of the
Raman spectra of GaAs with and without our phosphorus thin
film layer. That of the plain GaAs is sho~7n by dotted line
and GaAs, that having our phosphorus film, is shown by the
solid line.
'rhese data sug~ests a reduction of the surface barrier
of the GaAs when the phosphorus barrier is present. This
indicates that the phosphorus layer can be used in MIS and
Schottky devices and -Eor the improvement o~ the perfor~ance of
opto-electronic devices.
Figure 7 is a comparison of the line shape of the
photoluminescence of GaAs with and without a phosphorus thin
-12~ 110.007.1
C~724~ ~ C.7~73
film; GaAs alone is shown dotted; GaAs with our phosphorus
in solid.
It c~n be concluded from this diagram that there is
an increase of the electron concentration at the surface of
the GaAs when a phosphorus thin film is present. Since this
behavior is expected if the surface barrier has decreased,
this is consis-tent with the results shown in Figure 6.
Fi~ure 8 shows that there is an increase in the inten-
sity of the photoluminescence produced from GaAs when phos-
phorus thin film is present. The photoluminescence inten-
sity of GaAs alone is shown by the dotted line and intensity
with the phosphorus film is shown by the solid line.
This increase in photoluminescence again indicates a
decrease in number of surface states when the phosphorus
thin film is present. Thi.s result is consistent with
Figures 6 and 7.
The phosphorus film of Figures 6, 7, and ~ was gr~wn on
the C 111 ~ surface of GaAs specified by the manufacturer to
have 7 x 1017 free electrons per cubic centimeter.
We conclude that the GaAs surface barrier has been
reduced when a phosphorus thin f.ilm having a layer-like,
puckered sheet-like local order is deposited on the GaAs.
Our experiments indicate a reduction of one order of
magnitude in the density of the surface states.
The increase of the photoluminescence intensity we have
noted is extremely important for opto-electronic devices.
It means that there is a decrease in the surface recom~1-
nation velocity.
Thus we have shown that a polypnictide surface film
having a layer-like, puckered sheet-like local order deposi-
ted upon III-V semiconductors produces a reduction in the
density of surface states, allows the modulation of the
depletion layer; reduces the surface barrier, increases the
free electron concentration at the surface, increases the
photoluminescence intensity, and decreases the surface
recombination velocity~
-13~ 110.00-7.1
C.72~4 & C.7~73
Devices ~ccordinq To rrhe Invention
_
Now referring to Figure 9, a MISFET according to the
invention comprises a body of III-V semiconductincJ material
20, islands 22 of high con~uctivity, a conduction
channel 24 therebetween, source and drain metal ccntac-ts 26
sate metal contact 28, insulating layer 30 and passivating
layers 32.
Accordin~ to the invention the I layer 30 and the
passivating layers 32 which may be unitary and deposited on
the substrate 20 at the same time, are the new amorphous
layer-like phosphorus or other layer-li~e pnictide-rich
materials, such as MPl5 where M is an alkali metal and MPX
where M is an alkali metal and x varies from 15 to infinity,
particularly where the alkali metal is potassium.
Figure lO shows a ~SFET according to the invention.
This comprises a III-V serniconductor body 3~, islands 36 of
high conductivity, source and drain contacts 38, gate
contact ~0, conduction channel 42 and passivating layers 4~
according to the invention. The layers 44 reduce the
surface currents from the source and the drain to the gate.
According to our invention another MIS device utilizing
a III-V substrate may be formed as shown in Figure ll.
There the III-V substrate, generally indicated at 2, is
appropriately doped to form P regions 4 and N regions 6
therein. The polypnictide or elemental pnictide layer 8 is
then deposited thereon, according to our invention,
appropriately masked and etched, and then a metal such as
aluminwn is deposited to form drain lO, gate 12, and source
14. ~hose skilled in the art will realize that many other
MIS configurations and devices may be fabricated using a
pnictide-rich insulating layex according to our invention.
Most III-V semiconductor junction devices have ei-ther a
planar or mesa configuration where the ed~es of the
junction or junctions are exposed on the device surface.
~or some critical applications (e.g., PIN or avalanche photo
detector diodes for li~htwave communications), it is
imperative that the dark current (i.e., current with no
illumination) under operating reverse bias be as low as
-14- ~ 110.007.1
C.72~4 & C.7~73
possible in order ~o assure low device noise. Since the
surface current component of this dark current can be
significant, it is desirable to rninimize the surface current
through "passivation" of the surface (i.e., reduction or
elimination of surface current paths). This is done by
depositing a thin film of a suitable insulating material
onto the exposed device surface. Materials currently used
for this on III-V devices include SiO2, Si3N4, polyimide,
and pho-toresist, but none are able to eontrollably and
reproducibly reduce th~ surface current to -the very low
values needed.
According to our invention we use a thin film of
polypnictide material (e.g. 7 phosphorus, MP15, or MP where
x is 15 or greater and where M is an alkali metal sueh as
potassium) for III-V devices of this type. These materials
have: l) good physical and chemical stability, 2~ high
electrical resistivity, and 3) a preferred tendency or
"affinity" for the polypnictides to grow on III-V material
substrates.
Now referring to Figure 12, a body of III-V
semiconduetor material 46 containiny various layers has
metal contacts 48 and 50 deposited thereon. To reduce the
surface current component which would provide leakage
between the layers 52, 54 and 56 we deposit a film 58 of
pnictide according to our invention.
The deviee illustrated in Figure 12 may be, for
example, a P-I-N photo detecting diode or an avalanche
diode.
The deviee illustrated in Figure 12 has a planar
structure. A device having a mesa strueture is shown in
Figure 13. It eomprises various layer5 58~ 60, 62, 64, 66,
and 68 of III-V material and me-tal contacts 70 and 72.
Again, in order to preven-t surface currents aeross the
interfaces 74, 76, 78, 80, and 82 between the layers 58, 60,
62, 64, 66, and 68, we provide pnic-tide-rieh passivating
layers 84 and 86.
The device illustrated in Fiyure 13 may be for example
a photo deteeting P-I-N diode or an avalanehe doide.
~ .72~ ~ C.7~i3
Bo-th Fi~ure 12 and 13 illustrate the use of our novel
pnictide layers to lower surf~ce currents in opto-electronic
devices.
Another important application of our invention to
opto-electronic devices is based on the fact that our novel
pnictide layers reduce the surface recombination velocity ~t
the surfaces of III-V semiconductors to which they are
appli~d. We have noted an incxease by a fac-tor of 2.5 in
the measured photoluminescence intensity of heavily doped
GaAs with an amorphous thin film of layer-like puckered
sheet-like phosphorus grown on the <1l1> surface. This
increase in the photoluminescence intenslty indicates a
decrease recombination velocity at the surface. It is known
that the sma:Ller the surface recombination velocity the
better the performance of the opto-electronic devices such
as light emitting diodes, lasers, solar cells, photo
cathodes and photo detectors utili~ing III-V semiconductors.
According to our invention the layer of our new
layer-like form of pnictide-rich material would be applied
to the light emitting or light collecting surface of the
opto-electronic device.
Thus referring to Figure 1~, a light collecting device
according to our invention comprises a body 88 of a compound
intermetallic or III-V semiconductor comprising a pnic-tide
and a pnictide-rich layer 90 deposited on the ligh-t
collecting surface 92 thereof.
Similarly, as illustrated in Figure 15, a light emit-
ting device according to our invention again comprises a
body 9~ of a compound intermetallic semiconductor comprising
a pnic-tide-rich layer 96 deposited on the liyht emitting
surface 98 thereof. If the light collecting or light emi-t-
ting device has two or more semiconductor layers ~hich
emerge on the surfaces 9~ or 98 as indicated by the inter-
sections between them 100 and 102, then the layers 90 and 96
also reduce surface currents. The layers 90 and 96 m~y also
be used to reduce surface currents be-tween contacts, not
shown, as in the devices of Fîgures 9 through 13.
-16- ~ ~?o~ 110~007~ 1
C~o724~ E, C.7'173
Thus we have discl.osed the insulation and passivation
of compound and in-termetall.ic semiconductors comprising a
pnictide, particular~y III V semiconductors; disclosed a new
form of pnictide-rich thin films having a layer~ e, puck-
ered sheet-like local order; we have shown that such layers
when deposited on pnictide based semiconductors reduce the
density oE surface states, allows modulation of the
depletion layer, decrease the surface barrier, increase the
carrier concentration at the surface, increase the
photoluminescence, and decrease the carrier recombination
velocity at the surface; we have disclosed MIS and Schottky
devi.ces, particularly MISFETS and MESFETS utilizing pnictide
rich layers for insulation and passivation; we have
disclosed various electro-optical devices utilizing such
layers for insula-tion, passivation, increased performance
and lifetime.
The semiconductors utilized in our invention comprising
pnictides are commonly called intermetallic or compound.
III-V semiconductors which are compound, intermetallic,
semiconductors comprising elements from column III and
column V of the periodic table such as the binary
semiconductor aluminum phosphide, aluminum arsenide,
aluminum antimonide, gallium phosphide, gallium arsenide,
gallium antimonide, indium phosphi.de, indium arsenide and
indium antimonide, the ternary and the quaternary
semiconductors. By pnictide we mean those elements from
column V of the periodic table, namely nitrogen, phosphorus,
arsenic, antimony ancl bismuth.
It will thus be seen that the objects set forth above,
among those made apparent from the preceding description/
are efficientl~ obtained and, since certain changes may be
made in carrying out the above methods and in the articles
set ~orth without departing from -the scope o the invention,
it is intended that all matter contained in the above des-
cription or shown in the accompanyiny drawing, shall be
interpreted as illustrative ana not in a limiting sense.
-17~ .007.1
C.72~ ~ C 7~73
It is also to be understocd that the following claims
are intended to cover all of the generic and specific fea-
tures of the invention herein described, and all statements
of the scope of the invention which, as a matter of lan-
guage, miyht be said to fall the~ebetween.
Particularly, it is to be understood that in the claims
ingredients or compounds recited in the singular are in-tend-
ed to include compatible mixtures of such ingredients
wherever the sense permits.
Having described our invention what we claim as new and
desire to secure by letters patent is:
