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Патент USA US3048806

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Aug. 7, 1962
Filed April 30, 1957
2 Sheets-Sheet 1
ited Sëtates Patent Ó
Patented Aug. 7, 1962
art, flow between electrodes which establish an electro
static field. By immersing the semiconductor element in a
magnetic field, perpendicular to the electrostatic field, the
Ernest G. Linder, Princeton, NJ., assignor to Radio Cor
poration of America, a corporation of Delaware
Filed Apr. 30, 1957, Ser. No. 656,003
11 Claims. (Cl. 332-31)
charge carriers will flow in a magnetron-type motion, and
microwave oscillations may lbe sustained by la resonant cir
cuit in cooperation with the semiconducting element. By
varying the electrostatic field or by varying theV number
of charge carriers created, the generated microwave oscil
This invention relates to improved microwave apparatus
employing semiconducting elements. More particularly,
the invention relates to novel apparatus for producing 10
lations may be modulated.
The invention is. described in more detail in connection
magnetron-type microwave oscillations of charge-carriers
with the Vaccompanying drawings, in which:
in a semiconductor element subjected to a magnetic field.
Heretofore, the magnetron has been a vacuum tube
type semiconductor magnetron;
FIG. l is a schematic top section View of a split-anode
FIG. 2 is a schematic top section view of an optically
essentially of the diode type wherein the electrons flow
ing from the cathode to the plate under the influence of 15 excited semiconductor magnetron;
FIG. 3 is a schematic top section view of a semicon
an electric ñeld existing therebetween Vare made to follow
ductor magnetron excited by radioactive bombardment;
a cyclic or spiral path by means of a magnetic field estab
FIG. 4 is a schematic top section lview of a semicon
‘lished perpendicular to the electric field. The strength of
the magnetic field is increased beyond the point whereat
the electrons are caused to curve sufficiently to miss the
plate and follow a cyclic orbit. Oscillations at an ultra
high frequency are produced by virtue of the currents in
duced electrostatically by the moving electrons. As used
herein, the term “magnetron-type motion” is intended to
mean the flow pattern or movement of electrons or charge
carriers when subjected to mutually perpendicular mag
netic and electric lfields. The frequency of oscillation is
roughly determined by the time it takes the electrons or
charge carriers to perform a complete cycle of motion.
The ultra high frequency energy generated is transferred
to a load by means of an external circuit between the
cathode and plate of the magnetron.
A magnetron tube uses an evacuated envelope to pro
tect the thermionic cathode from exposure to air, and to
permit unimpeded electron flow in the tube. A magnetron
tube also may use a complex multiple cavity resonator
anode having sufficiently high Q to sustain oscillations in
the tube. A substantial heater current is required atleast
ductor magnetron using a multiple cavity resonator and
waveguide output;
FIG. 5 is a schematic top section view of a semicon-ductor magnetron `contained within an output waveguide;
FIG. 6A is a `schematic side section 'View of a semi
conductor magnetron utilizing a p-n junction device; and
FIG. 6B is ak schematic side view in section of another
embodiment of the semiconductor magnetron of FIG.` 6A
using »a pair of p-n junction devices.
Similar reference characters are applied to similar ele
ments throughout the drawings.
Referring now to FIGURE 1, a hollow cylinder 1 of
p-type semiconductor ymaterial is oriented» withits axis
perpendicular to the plane of the figure. The semicon
ductor may be germanium, silicon, gallium arsenide, or
indium phosphide, for example. intrinsically pure ma
g terials may be employed or the materials may be doped
with other elements to establish a particular type of con
ductivity. N-type conductivity, that is, current conduc
tion which is due to negatively-charged carriers or elec
trons, may be established in germanium or silicon by irn
initially to heat the thermionic cathode, and a very strong
magnetic field must be supplied by a magnet or solenoid. 40 purities having an excess of electrons in their valence
band such as phosphorus, arsenic, and antimony, for ex
In addition, the only practical methods for modulating
ample. PJtype conductivity, that is, current conduction,
a vacuum-tube magnetron are by varying the anode volt
which is due to positively-charged carriers or holes, may
age, or by modulating a second electron beam projected
tbe established in germanium or silicon by impurities hav
through the resonant structure.
An object of this invention is to provide improved 45 ing a deficiency of electrons in their valence band such
as gallium and indium. Gallium arsenide and indium
methods of and means for generating electromagnetic
phosphide may be made to have p-type conductivity by
waves in the microwave frequency range.
such impurities as cadmium, zinc or mercury; n-typ‘e con
Another object of this invention is to provide improved
ductivity is established in these semiconductors ‘by sulfur,
methods of and means for generating and modulating elec
selenium, or tellurium. Preferably, the semiconductor ele
tromagnetic waves in the microwave frequency range.
Another object of this invention is to provide improved
ment is single crystalline. Polycrystalline material may be
methods of and means for utilizing a semiconductor ele
ment for generating microwave energy.
A further object of this invention is to provide an im
optimum efficiency, the semiconductor material is pref
proved microwave generator which requires no evacuated
envelope in its structure.
Another object of this invention is to provide an im
employed although less eñiciently since crystal boundaries
will interfere `somewhat with charge carrier motion. For
55 erably selected to have its carrier mean-free-time no less
than a full period of oscillation at the operating frequency.
The material is formed into a cylinder by means of an
proved semiconductor microwave generator utilizing
ultrasonic wibratory cutting instrument, for example, al
Another object of this invention is to provide a micro
wave generator which may be modulated by a number
thickness ofthe cylinder may be about 0.2 mm. A metal
tubular member 5> is lfitted to contact the inside surface
of the hole 7 of the semiconductor cylinder 1 to constitute
though other techniquesmay be employed such as etch
charge-carriers subjected to a magnetic field.
60 ing. Illustratively, the cylinder may be about 1 mm.
Another object of this invention is to» provide a micro
high and have a diameter of about 0.5 mm. The wall
wave generator requiring no thermionic cathode.
of techniques in addition to varying the anode voltage.
These and other objects and advantages may be ac
complished in accordance with the present invention by
apparatus wherein magnetron-type motion is imparted
to charge-carriers in a semiconductor element. When an
65 a cathode electrode and to form a metal-semiconductor
contact. rThe contact, in the instant embodiment, may be
either ohmic or rectifying. In either instance it serves
the dual purpose of cooperating with the outer metallic
electrostatic iield is impressed across the semiconductor 70 plates 3` and 4 to establish an electric field through the
semiconductor body 1 and to inject charge carriers into
element, charge-carriers, which may be created therein by
the semiconductor. The tubular member 5 may be in
means and techniques wellllrnown in the semiconductor
'pressure contact-with the inside of the semiconductor
cylinder 1, or it may be constituted by a plated metal
layer thereon, or it may be soldered thereto. Metallic
Light energy from a source represented by the light bulb
23 irradiates the semiconductor element 1 and also falls
on a solid transparent rod‘25 which may be made of
plates 3 and 4 in the form of cylindrical segments contact
quartz, for example. The quartz rod 25 is coated with a
y'the .outside surface of the cylinde'rto constitute anode 5 transparent conducting layer 27, the outer surface of this
electrodes of the split-anode type. A two-wire transmis
-layer contacting the inner surface of the semiconductor 1.
sion line, formed by the conductors 11 and terminated by
'the terminating 4conductor or tuning element 13, Yis. con
'nected to the` anode -electrodes 3 and 4 thus forming a
A concentrating lens 29 may ybe used to increase the light
intensity incident on quartz rod 25. Light falling on the
semiconductor 1 may partially penetrate the semiconduc
"resonant section of line. >The tuning element 13 is moved 10 tor, which has some transparency to light. The quartz
along between the conductors 11 to adjust the' inductance
'of the l’oop 11, 13,11 and thus to vary the frequency of
oscillation. The power supply/15 is connected to the
'tulbular member 5 or cathode and to the midpoint, or
rod 25 conducts light along its length by means of multiple
internal reiiection. Thus light energy irradiates the inner
surface of the semiconductor cylinder 1 adjacent to the
quartz rod 25. An electrostatic field is established with a
voltage node, of the tuning element 13. Thus the trans 15 radial potential gradient in the semiconductor element 1
mission line conductors 11 and the split anodes 3 and 4
by means of electrodes V3 and 4 and the internal electrode
are maintained at a suitable anode voltage such that the
27 which is constituted by the transparent conducting
charge carriers will make one or more cycles of motion
layer located internally With the semiconductor element 1.
before reaching the anode. The voltage required will de
The electrodes 3, 4 and 27 are connected to the power
~pend upon the desiredfrequency to be generated, the di 20 supply 1'5 so as to maintain an anode voltage sufficient
mensions of the semiconductor body, the eiîective mass
to cause the charge .carriers to make one or more cycles
of the charge carriers (which is determined by the kind
of motion before reaching the anode. VIt should be ap
of material), and by the mod_e of operation (i.e., split
preciated that if the semiconductor element 1 is of p-type
anode mode, low-iield mode, etc.). The potential differ
conductivity and the central electrode 27 is made negative
ence between the cathode tubular member 5 and the anode 25 with respect tothe semi-cylindrical electrodes 3 and 4,
electrodes 3 and 4 forms an electrostatic Alield having a
then negative charge carriers or electrons will flow from
radially directed potential‘gradient in the semiconductor.
the cathode electrode 27 to the anode electrodes 3 and 4.
In ‘this embodiment, the tubular member 5 acts as a source
On‘the other hand, by making the central electrode 27
of electrons (since the semiconductor element 1 is of p
positive with respect to semicylindrical electrodes, 3 and 4,
type conductivity) due to one or more of the effects of 30 then positive charge carriers or holes will ñow from the
carrier injection, ñeld breakdown, and impact ionization
anode electrode 27 to the cathode electrodes 3 and y4. If
caused by the radial potential gradient in the semicon
the semiconductor element 1 is of n-type conductivity and
ductor cylinder. As is known in the art, the polarity of
.fthe central electrode 27 is negative with respect to the
the applied yvoltagel and the type of semiconductor deter
semi-cylindrical elements 3 and 4, then negative charge
mine'whether either electrons or holes are generated. 35 carriers or electrons will flow from the cathode electrode
Hence, in the present embodiment, wherein p-type ma
27 to the anode electrodes 3 and 4. Conversely, positive
terial is employed, the tubular electrode 5 is made nega
charge carriers or holes will flow from the central elec
rtive with respect to the semi-cylindrical electrodes 3 and 4.
trode 27 to the semi-cylindrical electrodes 3 and 4 if the
A magnetic field is estalblished in the semiconductor
_central electrode 27 is positive with respect to the semi
element 1 by =a solenoid coil 8, for example. The ñeld 40 cylindrical electrodes 3 and 4. A magnetic ñeld whose
‘established is parallel to the axis of the cylindrical element
lines of force are perpendicular to the direction of the
1, and the lines of force of the magnetic ñeld are per
electrostatic rfield is established by the solenoid coil 8, for
pendicular to the radial potential gradient of the electro
example, which is coaxially disposed around the semi
static iield. Hence, the flow of current from the tubular
conductor cylinder Y .
electrodeS yto the electrodes 3 and 4 is thus modified by 45
Radiation from the light source 23 causes the release
the presence of the magnetic lfield, and the trajectories of
of electrons or holes in the semiconductor by optical ex
the electrons assume a magnetron-type path. The strength
yof the magnetic field must be sutlicient to give cyclic mo
citation of electrons into the conductive band. A current
of electrons or holes thus flows in the semiconductor to the
tion «to the electrons at the frequency desired to be gen
electrodes 3 and 4 in magnetron-type paths as described
erated. The resonant circuit 11 and 13, acting together 50 previously. The remainder of the operation of the res
with the current in the semiconductor, »sustains micro
onance circuit, the output coupling lines and the micro
wave oscillations. The portions 17 of the transmission line
Wave load are the same as have been described previously.
formed by the conductors 11 form an output circuit cou
The semiconductor magnetron may have its operation
pled to themicrowave load 18.
considerably enhanced by cooling it. Lowering the tem
_Referring again to FIGURE l, in a modification of the 55 perature reduces latticescattering in the semiconductor
split-anode embodiment ‘of the Vinvention iirst described, a
crystal and thus produces a ylonger mean free path which
heater v9, located internally
the semiconductor ele
permits the electrons or holes `toachieve a larger number
ment 1, heats the -tubular member 5 :and the portion of
of cycles of motion without disturbance due »to scattering.
the semiconductor adjacent thereto resulting in thermionic
Hence the semiconductor magnetron may be contained in
excitation of electrons or holes in the semiconductor. 60 a cooling device represented bythe dotted >lines 10. The
Thus in this embodiment the tubular mem-ber 5 may but
cooling device may be a Dewar flask, for example, in
does nothave -to function as a means for injecting charge
carriers into the semiconductor; its primary function is to
cooperate with the metallic plates 3 and 4 in establish
ing an electric field through the semiconductor. Leads 21
apply a suitable voltage for heater operation to the heater
9. The magnetic and electrostatic fields are established
as beforepandcause the emitted electrons to move in
magnetron-type paths as described, supra.
The opera
tionV ofthe resonant circuit, the output coupling lines and
the electrodes 3 and‘S- are the same as in the iirst embodi
Referring to FIGURE 2, another embodiment with a
cylindrical semiconductor element 1 is now shown partial
ly in section with its axis lying in the plane of the figure.
which the semiconductor device 1 is contained and su‘b
v stantially surrounded by liquid nitrogen or helium, for
Another embodiment is shown in FIGURE 3 wherein a
metallic or electrically conductive tube 5 is passed through
the semiconducting cylinder 1 and is filled with a radio
active material 31. The end caps 33 Iare provided on the
tube 5 to retain the radioactive material. The end sur
faces of the semiconductor cylinder 1 may »also be coated
with radioactive material 35. Electrons or holes are
released within the semiconducting material by radio
active bombardment. The electrostatic iield is established
as described heretofore. The magnetic field H is estab
lished by means of the magnetic pole pieces 34 and 47 so
that the ñeld is substantially perpendicular »to the electric
tield. The electrons or holes ñow in magnetron-type paths,
and the resonant circuit and output coupling means'to a
microwave load are the same as those described pre
In another embodiment, shown in FIGURE 4, a semi
conducting cylinder 1 is coaxially oriented within a mul
tiple cavity type resonator 41. The semiconductor cylin
der 1 contacts the inside portions 45 of the cavity resonator
ductor device 61. Iif the waveguide portion 67 is made
negative with respect to the contact member 71, then
negative charge-carriers (electrons) migrate from the
junction `69 through the p-type region 64 toward the con
tact member 71, due to the electric field in the material.
If the polarity is reversed, then positive charge-carriers
(holes) -will flow from the junction through the n-type
region 66 toward the waveguide portion 67. The path
of the electron or hole llow is modified by the presence
which lie between individual cavity slots 47. The con 10 of the perpendicular magnetic lield, and magnetron-type
trajectories result. One such trajectory of electrons is il
tacting portions 45 -function as «anode electrodes and are
lustrated at 77. These electrons in cyclic trajectories
an integral part of the resonator 41. The cavity slots 47
sustainmicrowave generation, similar to that in magnetron
sustain microwave oscillation. A microwave coupling
vacuum tubes. The microwaves are propagated in the
means 49 provides a tapered transition to a waveguide
portion 51 and is coupled to one of the cavity portions 47 . 15 waveguide 63 to the-microwave load 18.
In FIGURE 6B a double junction 72 is shown which
Microwave energy is delivered to a microwave load 18
may be incorporated in the ywaveguide apparatus of
FIGURE 6 in lieu of the single junction device 61. The
device 72 actually comprises a pair of p-n‘junction devices
by means of the lsource of power 15 which is connected
to the tube S and the resonator 41. A magnetic iield is 20 so arranged that «their respective n-type regions 73 and ’75
through the waveguide coupling means 49. An electro
static lield is established with a radial potential gradient
established by means of a solenoid 8l coaxially disposed
around the resonator-semiconductor assembly.
contact a common electrical conductor 74. The p-type
regions 76 and 78 are contacted to the contact member
67 andwaveguide portion 71, respectively, as in the em
bodiment of FIGURE 6A. The power supply 15 is con
Referring to FIGURE 5, Va semiconductor cylinder 1 is
completely contained within a waveguide 53. Arcuate 25 nected _to the central electrode 74 and to the contact
` member 67 andthe waveguide portion 71 as shown. If
electrodes 3 and 4 contact the outside surfaces of the
the central electrode 74 ismade negative with respect to
semiconductor cylinderl. A tubular member 5 contacts
the contact member y67 and the waveguide portion 71,
the inner surface of the semiconductor. , The arcuate elec
netron-type current flow occurs here as described before.
trodes 3 and 4 and the tube 5 are connected to a power
source 15l to provide a radial potential gradient in the
semiconductor cylinder as has been described. A lead V55
then negative charge-carriers (electrons) will migrate
30 from the junctions 80 and 82 through the p-type regions
76 and 78, respectively toward the contactÍ member 67
passes through the waveguide wall and is electrically
insulated therefrom by the insulator S6, connecting the
and the waveguide portion 71, respectively. Likewise,
positive charge-carriers (holes) will migrate through the
of the waveguide wall which, in turn, is also connected
with this arrangement.
tubular member 5 to the power source 15. The electrodes 35 n-type regions 73 and 75 toward the central electrode 74.
Oscillations of much higher current are thus obtainable
3 and 4 are connected by leads 57 to appropriate portions
by leads -to the power source 15. The portion of wave
guide contacting the leads 57 'functions ras a resonant
It should be appreciated that much higher ‘frequencies
may be generated by the `semiconductor magnetron device
described 4than the Áfrequencies generated by a vacuum
type magnetron because the- effective mass of charge
3 as described.' Microwave energy is propagated down
carriers (electrons or holes) in a semiconductor is less
the waveguide 53 to a microwave load 18.
than the effective mass of electrons in free space or
Another embodiment is shown in FIGURE 6A wherein
vacuum. Frequencies obtainable with vacuum-type mag
a semiconductor p-n rectifying ljunction device 61 is im
mersed in a magnetic «field‘ established `b-y means of the 45 netrons are also obtainable with the semiconductor -mag
netron device described herein but at electric and magnetic
magnetic pole pieces 70 and 74. The semiconductor junc
circuit. The magnetic iield is established by the solenoid
iield strengths substantially lower than the iield strengths
tion device 61 is contained in a waveguide section 63 which
is tapered to a smaller portion 67 to provide impedance
matching. The semiconductor junction device 61 is com
required by the vacuum-type magnetrons.
so that they form a p-n rectifying junction 69 at the inter
of the light'source 23 in the embodiment of FIGURE 2;
The semiconductor magnetrons shown and described
posed of a p-type region 64 comprising germanium doped 50 herein may have their outputs modulated by varying the
anode voltage. Modulation may also be achieved by
with arsenic, yfor example, an n-type region 66 comprising
varying the number of charge-carriers created in the semi
germanium doped with indium, for example. 'I'hese
co-nductor body las, `for example, by varying the intensity
regions are fused together or otherwise contact each other
face between the p-type and n-type regions. The n-type
region is in electrical contact with the ywaveguide 63 at the
>portion `67 thereof,>and the p-type region is in electrical
Contact to the electrically conductive contact member 71.
The power supply 15 is connected to the waveguide 63
and the contact member 71, and impresses a potential dif
ference 'across Ithe semiconductor junctionfdevice 61 by
supplying voltage between the contact member 71 and
the waveguide portion 67. The contact member 71 vis
electrically insulated from the waveguide 63 by the gaps
73. 'Iîhe waveguide characteristics of continuity of micro
wave propagation are maintained by capacitive micro
the light beam might also be chopped-as by the chopper
12 or deflected at the desired modulation rate.
A third
way of modulating the device is by varying the tempera
ture as, for example, in the embodiment of FIGURE l
wherein charge-carriers »are thermally produced. Vary
ing the temperature of the heater 9 (as by varyingV the
heater current supplied thereto) modulates the output of
vthe semiconductor magnetron device. Changing' the
temperature ofthe- semiconductor magnetron changes the
number of electrons and lcharge-carriers to be raised lf_rorn
the conduction to the valence band, for example. Hence
the device reacts to produce a larger or smaller number
of charge-carriers in response to temperature changes.
By varying the anode voltage in the embodiment of
waveguide 63 `across the gaps 73. An impedance matching
FIGURES 6A and 6B, the bias across the junction (or
adjustment is provided by the sliding conducting plug 75
which makes contact to the walls of the waveguide 63. 70 junctions) is also changed, the result of which is to
determine the number of minority charge-carriers injected
A magnetic ñeld is established perpendicularly to the elec
across the junction (or junctions). Thus modulation of
tric ñeld by means of the tapered magnetic pole pieces 70
these junction-type magnetron devices is achieved by 'a
and 74, for example, the magnetic lines of `force curving
wave coupling between the contact element 71 and the
two-fold effect: (l) a varying anode voltage and (2) a
down and through the device 61. v In operation, carrier
injection occurs at the p-n junction 69 in the semicon 75 varyingv bias `across the junction.
There thus has been shown and described a novel and
improved magnetron device which does not require a
trode for said semiconductor body cooperating with said
vacuum tube or thelike and whichdoes not require a
body perpendicular to said magnetic field, a tunable
microwave resonant structure coupled to said body, and
a microwave waveguide section coupled to said> cavity
anode electrode to establish an electrostatic ñeld in said
thermionic cathode and the concomitant substantial heater
current. The semiconductor magnetron described herein
is capable of operating at higher frequencies while requir
ing relatively lower electric and magnetic iield strengths,
anode electrode by means of `one of said slots.
and several methods of modulating the output of the de
vice have been described.
drical semiconductor body immersed in a magnetic iield
7. Apparatus comprising in combination a hollow cylin
whose lines of force are parallel to the longitudinal axis
10 'of said body, means `for generating free charge carriers in
said Ibody, `a cylindrical cavity anode electrode surround
1. Apparatus comprising in combination means for
What is claimed is:
ing said body forming a plurality of slots therewith, a
providing a magnetic lñeld, a semiconductor body _im
mersed in said magnetic íield, a source of charge carriers
cathode electrode disposed within said cylindrical semi
in said semiconductor body, and means lfor causing sard
conductor body and cooperating with said anode electrode
charge carriers to travel along a spiral path including
' to establish a radially directed electrostatic iield therein,
anode and cathode electrodes for said semiconductor body
for producing an electrostatic ñeld therein which is sub
stantially radial `around a central axis thereof and sub
body, Yand a microwave Vwaveguide section coupled to said
a tunable microwave resonant structure coupled to said
cavity anode electrode by means of one of said slots.
8. A semiconductor «device comprising in combination:
transmission means coupled to said body, and a micro 20 a semiconductor body, means for producing charge car
riers in said body, means for establishing yan electro
wave load coupled to said transmission means.
static iield in said body including a separate source of
2. Apparatus comprising in combination means for
radiant energy and means for directing said radiant en
. providing a magnetic iield, a-semiconductor body im
ergy from -said source upon said semiconductor body,
Y mersed in said magnetic field, means for generating free
means for simultaneously establishing a magnetic ñeld in
chargecarriers within said body, anode and cathode elec- 1
said body perpendicular >to said electrostatic Íìeld, a micro
trodes for establishing an electrostatic field in said semi
wave resonant structure operatively associated with said
conductor body perpendicular to said» magnetic field`
body, microwave transmission means coupled to said '
, whereby'spiralfcurrent ñow is sustained in said semi
conductor fbody, and an electromagnetic wave resonant
body, and a microwave load coupled to said transmission
circuit coupled to said electrodes, :and means for pro l350
9. A‘semiconductor device according to claim 8 com
viding charge carriers near said cathode.
stantially perpendicular to said magnetic field, microwave
prising optical energy means yfor, producing free charge
:3. A semiconductor device comprising in combination
a semiconductor body, a tunable microwave resonant
carriers in said body.
structure coupled to said body, means for generating free
charge carriers in said body, means for imparting spiral
motion to said charge carriers, microwave transmission
l10. A semiconductor device according to claim 8 com
prising radio-active means for producing free charge car
riers in said body.
»11. A semiconductor device Iaccording to claim 8 com
means coupled to said body, and a microwave load cou
pled to said transmission means and means -for modulat
prising thermal means for producing lfree charge carriers
in said body.
ing the output of said device.
4. A semiconductor device comprising in combination 1'
a semiconductor body, a tunable microwave resonant
structure coupled to said body, means for generating
free charge carriers in said body, means -for imparting
spiral lmotion to said charge carriers, means for modulat
ing the creation of said charge carriers, microvrave'trans
References Cited in the ñle of this patent
mission means coupled to said body, ‘and a microwave
Vload coupled to said transmission means.
5. Apparatus comprising in combination a semicon
ductor body, means for `generating `free charge carriers in
Da_rrah ______________ __ May 3, 1932
Linder ____ __ _________ __ Aug. l, 1950
Wallace _____________ __ May 15, 1951
Schwartz ______________ __ Oct. 5, 1954
*Haynes ___________ _____ Oct. 12, 1954
_ 2,695,930
Wallace _____________ __ Nov. 30, 1954
said body, an anode electrode for said semiconductor :_ R0
j ì 2,743,322.
Pierce et al. _____ ________ Apr. 24, 1956
Pankove _____________ __ July 23, 1957
Pankove ____________ __ Feb. 25, 1958
body «forming 'a Yplurality of slots therewith, a cathode
'electrode for said semiconductor body and cooperating
with said anode electrode to establish an electrostatic ñeld
~. Íin said semiconductor body, va tunable microwave reso
Gunn et al. __________ __ Nov. 3, 1959
Matare ______________ __ July 5, 1960
France ___ ___________ __ Sept. 3,’1956
nant Structure coupled'to said body, means for establish F155
ing a magnetic Viield insaid semiconductor body perpen->
dicular to said electrostaticñeld, microwave transmission
means coupled to said body, and a microwave load cou
Apled to `said transmission means.V
6. 'Apparatus' comprising in combination a semicon »60 I’Sllhe Physical Review, October 15, 1953, pgs. 215 to
'ï‘ductor ybody immersed in a magnetic field, means ffor »gen
`erating free charge carriers in said body, ya resonant cav
ity'anode electrode surrounding said semiconductor body
and ~forming a plurality of slots therewith, a cathode elec
“Transistorsg Theory -and Application,” by Coblenz et
al., published by McGraw-Hill Book Co. Inc., New York,
N.Y., pgs. 249-254,
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