US2610234A - Crystal triode - Google Patents

Description

Sept. 9, 1952 A. H. DICKINSON CRYSTAL TRIODE 2 SHEETS-SHEET l Filed May 4, 1950 .n//onn7/////////// Y FIG. 3.

Sept. 9,' 1952 A. H. DlcKlNsoN l 2,610,234

CRYSTAL TRIODE Filed May 4, 1950 2 SHEETS--SHEET 2 FIGS.

E, 0.4 VOUS 5e O3 VOUs COLLEC TOI? CURPEN 7 /N M/C/POAMPEPES 'b /0 /5 2O 25 J0 35 40 COLLCTOP VOLTAGE /N VOLTS Flo'.

E, =/,2 VOUS e =O.9 VOUS f5 E, =0.6 VOUS f0.3 VOUS 5, =O VOUS COLLECTOAD wmf/vr /N M/LL/AMPL-"M5l COLLECTOR VOLMGL' /N VOLTS INVENTOR ARTHUR H. D/CK/NSON Patented Sept. 9, e1952y 2,610,234 (s CRYSTAL 'rmonn Arthur H. Dickinson; Greenwich, Conn., assigner to International Business Machines Corpora tion, New York, N. Y., a corporation of New York i Application May' 4, 195o, seria; No. 159,980

This invention relates to -semi-cc'mductor's and more particularly to a'novel crystal triodef' A conventional crystal triode or transistor includes two small Vdiameter electrodes in theform ofil whiskers resting `on one face ofea crystal, vusually ofthe high back voltagegermanium type, and a third or base electrode of relatively large area and low resistanceconnected tothe other rface of the crystal; When the two`1whiskers,

termed emitter and `collector respectively, 'are placed in close proximity to each other on the face of the crystal andthe proper direct current bias voltages are applied to them thereis va mutual inuence which permits the deviceto be-used asian amplier. SuchY devices have Van output impedance of higher value than Vthat of the input impedance. "This feature lof' such crystal triodes requires the use `of impedance matching, amplifying or buier circuits if power gain is required. l Y

It is a principal object of the invention to provide a novel crystal triode which minimizes the above objectionable features.

Another object is to provide a crystal triode having a collector electrode which makes a substantially continuous line contact with'one face of the crystal.

Another object is to provide a crystal triode having an electrode arrangement such that the omnidirectional electrical field produced by one electrode is utilized to effect an increased electrical output from the triode. i

A further object is toprovide a-novel crystal triode having a low `output impedance so that its use at high frequencies is more feasible.

A still further object is to provide a crystal triode havingan output electrode in circumferen tial'spacedwrelation to anlinput electrode, the back resistance and the other electrical conditions `of the output'el'ectrode being variable "in response to variations in the electrical conditions of an' input electrode. l l

`Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings,` which disclose, by way of examples, the principle of the invention and the best mode, which has been contemplated, of applying that principle.`

In the drawings: Y

Fig. 1` is across sectional view of one embodiment of the invention, l

Fig. 2 is a top view of the embodiment shown in Fig. 1,

`Fig. 3 is an enlarged view of the portion of Eig. `1 included within the closed dotted line I0,

a claims. (ci. iis- 366) 2 l Y Fig. 4 is a conventional circuit 'diagram illustrating the character of the invention therein,"

Fig. 5 shows a set 'of characteristic curves wfor a conventional crystal triode, and u i .l

`ligfshows a setof characteristic curves for 'the crystal triode of the` invention.y 71

Referring more particularly to Figs. 1', 2 and'B", there'is shown av crystal receptacle suitable for use with the novel crystal trioder of thejinvention. A hexagonal member I2 is formedr tore'- ceive the insulating member I 4 and lexternallyy threaded member I6 having a lug IB'jsecured thereto by any suitable means toins'ure ag'ood electrical connection. 'I'he members I2, I4-andl6 are joined together, as shown, to prevent anyrellative movement between them [by any suitable means such as cement. The members I2,*I4fand I6 thus forma single inner member generally designated l I9 which has its inner portion bored out to receive a rod A2l). Screw"22 is threaded through member I2 to bear against the rodZIl to hold it securely in place. A crystal 24 is soldered on theupperend of rod 2U and terminal 26 is securedto the lower end ofvrod 2li by any suitable means such as a screw. g iSleeve 28 is internally threaded toV snugly engage the external threads of member I6 and ine cludes an inwardly extending lip `3Q. insulating member 32 and conductive member V3lI are mounted outward from sleeve 28,'members- 32 and 34and sleeve 28 being joined together by any suitable `means to'prevent relative movement between them and form a single outer member generally 'designated 35. Y l A disc shapedcollector electrodeA V36fli'avin'ga diameter approximating that 'of' memberl I6 is placedoverthe upper end of the inner'nember 'I9 and the outer member 35 screwed-.thereon u n-ftil the lip 30 clamps the disc 36 firmly against member I6. An arm 3B extends "inwardly from the'member `3i andincludes a terminal 4b con- -ductively connected thereto. A rod 42 is attached toand extends downward from the arm 38 and `terminates near the crystal 24. l

A conventional type Whisker 44 is affixed to rod 42and extends downwardin line with the center ofdisc 36 to serve asan emitter electrode. The electrode disc 36 may be formed by pricking it at its center and then drilling it to forma contin-` ous line or circular knife-edge. Obviously the Whisker passes between the circular knife-edge at the center defined by the circumference thereof and makes contact With the crystal 24. A'I'he rod 20 is moved within the member I2 untilbotlr the knife-edge of the electrode disc 36 and "the'point of the Whisker 44 are in contact with the upper face of the crystal 24. The screw 22 is tightened to hold the rod rmly in place and thereby maintain the adjustment of the crystal 24 relative to the electrodes 36 and 44. A typical diameter of the knife-edge may be 0.004 to 0.005 inch. f r v 1 Referringto Fig. 4, a battery 50 in series with a potentiometer 52 is connected between the emitter electrode 44 and the base electrode 20. The battery 54 in series with a potentiometer 56 is connected between the base electrode '20 `4 electrode and a collector electrode in continuous line contact with the crystal and in circumferential spaced relationship with the emitter electhe emitter voltage curves represent emitter voltage values from O to 1.2 volts in intervals of and the collector electrodeBB. As seen from 'the Y circuit arrangement, the emitterelectrode 44 is biased in a positive or forward directi'on'so AVthat a D. C. current flows into the crystal 24. The

collector electrode 36 is biased in a negative -or` reverse direction with a higher voltage than the bias voltages on the emitter electrode so 'that a D. C. current flows into the collector electrode.

A1t is well vknown that 4current through the collector electrodey issensitive to and may lbe vcontrolled by changes of `current from the zemitter electrode. lA-.change in the emitter voltage `EL may be effected by conventional movement of the arm of potentiometer v52 to change the emitter current and if the collector voltage E@ is kept `constant the change in collector current Vmay be larger than the change in emitter current. If` desired, after proper .adjustment of the potentiometers 572 and 56 an A. C'. voltage may belsuperimposed in any conventional manner on the.D.- C. voltage Ee to thereby -yary the emitter current -to cause an increased variance lof the collector current. Y

. .Aachange in thercollector current as a result l of :a 'change in the emitter-current ,is attributed -to 1several phenomena. Within the crystaL'the A.emitter current is thought to be providedlargely by positive charges, `referred to as holes. The ,collector current, in the absence .of any emitter current, is provided exclusively/by electrons.

The electric field ,associated with the collector current attracts the holes toward the collector and they aiect the collector'current in two ways. Firstly, the contact between the collector and .crystal does not impede the iiowof holes so that they add directlyto the collector current. Secondly, the positive charge is believed to modify the contact between the collector and crystal so that Y.it becomes easier for electrons to flow out ofthe collector. Y V

It isknown that the effectiveness vof this action is dependent among other things upon impurities in. the crystal, the bias voltage, the magnitude of the collector current, 'the temperature, the `electrode, arrangement, the electrode spacing andthe .contactbetweenthe crystal and the electrodes. .o .Referring to Figs'.V 5 and 6, there is demonstrated the superior performance of the semiconductors of the invention `as compared tothat ofV the` conventional semi-conductors using Whisker type electrodes as emitters and collectors. V

5 shows .the collector current in micro- .amperes for ,various values of Ycollector voltage in l;-volts when the emitter voltage Es is varied from .0 volt to 0.4 volt in .0.1 volt intervals. .These curvesrepresent the curves normally obtained when va lgermanium type crystal was used and both the emitterv and collector electrodes were in the formof whiskers. Y f rFig. 6 shows the curves obtainable Whenusing asimilar type crystal, a Whisker type emitter trode as taught by the invention. Here, the collector voltage is drawn to the same scale as in Fig. 5 but the collector current is given in milliamperes and so drawn that the current represented by a given distance along the ordinate is equal to times that represented by the same distance along the ordinate of Fig. 5. In Fig. 6

0.3 volt.

' The tremendous increase in output obtained by a practice of the invention can be readily appreciated by considering, as an example, the curves representing an emitter voltage of 0.3 volt when the collector voltage is 20 volts. It is seen that for Athese values the collector current indicated by Fig. 5 is approximately 60 microamperes and that indicated by Fig. 6 is approximately 9 milliamperes or 9000 microamperes. In other words, the current output made possible bythe novel collector electrode Aof the invention `is approximatelytimes that obtained by 'a comparable crystal -triode using conventional type Whisker electrodes.

The circumferential arrangement of the collector electrode of the invention Vwith respect to the emitter electrode provides an increased area of contact between the collector electrode' and the crystal ascompared to that of the crystal triodes of the two Whisker type. Iiowing through a crystal triode contact is substantially proportional to the area of thecontact .provided other features effecting such current flow remain unchanged. Such is demonstrated bythe curves of Fig. 6 as compared to those of Fig.y A5.

The higher collector current provided rby a practice of the invention, when the emitter voltage is 0, also provides a collector current having a greater rate of change with a changing vemitter voltage than that obtained -by the `two Whisker type crystal triode using a similar crystal. This is attributed to the greater vutilization by the invention of the holes introduced at the emitter. This increased utilization is made possible because the increased magnitude o-f the eld of the collectorcurrent causes an increased number of holes to reach the collector ,before'they combine with electrons. The larger the collector current, the largerthe number ofholes it can carry without the positive space Vcharge .of the holes reducing the field to such an extent Ythat a .large fractional part of additional holes .'is 4attracted to the base rather than to the collector.

Also inthe two Whisker type'crystal .trode the path of'traverse ofthe holes between'the emitter and collector is of diierent length Ybecause of the unsymmetrical effect of the eld produced ybythe collector current on the holes as they are injected by the emitter. As a result, many of the holes combine'with electrons before the holes reach the collector and can vtherefore make no contribution toward increasing the collector current. In vthe novel crystal triode of the invention Tthe holes at the emitter Vare'iniiuenced by a lsubstantially uniform iield created as a result of the ygeometric 4coniguration of the collector electrode. Accordingly, a larger number .of the holes are utilized to `increase the effect of the emitter voltage on the collector current.

While there have been ,shown :and .described and pointed out the fundamental novel features The current Y j of the invention as applied to a preferred embodiment, it will be understood that `various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. In a crystal trode; a crystal having a plurality of planar surfaces; a base electrode electrically and mechanically connected to a iirst face of the crystal; an emitter electrode mounted in point contact with a second face of said crystal; a resilient disc-shaped collector electrode in spacedl relation to said emitter electrode and having a substantially continuous line contact surface substantially parallel to said second face; mechanical means for holding said disc-shaped collector electrode and said emitter electrode in a preselected spaced relationship; and a member 6 having said base electrode ailixed-thereto, said member being longitudinally movable relative to said mechanical means so that the selected move ment thereof causes a preselected pressure to be exerted between said emitter and collector electrodes and said second face of said crystal.

2. The crystal triode set forth in claim 1 Wherein said member is rotatable relative to said `rnechanical means so that said line contact is movable on the face of said crystal to utilize particular electrical characteristics thereat.

ARTHUR H. DICKINSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 20 2,524,033 Bardeen Oct. 3, 1950 2,524,035 Bardeen et al Oct. 3, 1950

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