SU650131A1 - Bipolar shf transistor - Google Patents

Description

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The drawing shows the construction of such a plenary p-n-three n-resistor and the following notation is accepted: 1 emitter region; 2 - base area; 3 - alternating reservoir layers with different C; 4 - low impedance nodlozhka; 5, 6, 7 - emitter, base and collector} 1st electrodes, respectively; 8 dielectric film.

T (; orthic. Analysis showed that the use of a reservoir with a layered structure can significantly weaken the transient effects in the collector area, which reduce the limiting frequency f.

the effect of transient effects is associated with a decrease in the induced high-frequency current in the collector circuit 3 with increasing time T and angle 0 and) 1Г | the passage of charge carriers through the combined layer of the collector pn junction. In known transistors, in which the collector is made of a single semiconductor material, the induced current 3c is proportional to the transient multiplier

,

(one)

rapidly decreasing from 1 to O as the angle O increases from zero noiSi. If the combined collector layer occupies an area including n semiconductor layers differing in the values of dielectric constant C; then, as the theoretical analysis shows, the dependence of the current induced in the collector circuit on the electron flight angles in these layers O is determined by the factor

M, (o),) J. fe. ) - rneVj V / T | is the angle of flight of carriers through the semiconductor junction with the dielectric constant j. Formula (2) is decanted for the case when the electric field in the combined collector region is large enough (Yu kV / cm) in order to saturate the drift velocity of the current carriers Vj Vjj.

At given operating frequency L, thickness L of the combined collector region and the interval of variation of the dielectric constant G. ,, ts: gs

mm 1 (Poi 2

The multiplier M takes the greatest value for a multilayer structure consisting of alternating layers of two semiconductor materials with dielectric permeability S. and Cu thicknesses ensuring equal angles of current carriers through each layer, x) -02 5. In this case, formula (2) gives

1-V;

  n (, (z.fcos.o) V

a-.n.of

fY

(3)

H. (

-0 when

(nW | - | 74f

(four)

Thus, in a multilayer collector with certain layer thicknesses corresponding to equal flight angles, the span factor turns out to be independent of the number and n layers, i.e., the thickness of the combined layer of the collector p-n-junction. The magnitude of the transient multiplier increases with the increase in the difference in the values of the dielectric constants of semiconductor layers, approaching M М ViFf P 1

Claims (2)

 The semiconductor materials from which a multilayer collector is formed may differ not by dielectric constants, but by the values of saturated drift rates of charge carriers. If, for example, 2 oVi-C V ,, then with equal angles of flight O. l) l), the transit factor is determined by the expression / fV nrJlti -nW-I IU--) () si-, k) (5) or x) "2 AL" (I). H, in the case of V, V i 2 I / I (-0 coik)) +. (| H) Smk,) f M t An example of semiconductor materials from which a proposed multilayer collector can be made, can be gallium arsenide and a solid solution of gallium arsenide and aluminum arsenide. In the first case, the saturated electron velocity is about (O, 8-1) : 10 cm / s in the second (when the content of arsenide was about 60% galli) —about O, 3-1O cm / s. The dielectric constant values in both materials are approximately equal. The lattice parameters of both materials are close to each other; therefore, at the boundaries of the layers during their epitaxial growth, defects of structure n arise. Thus, the use of a multilayer collector made up of several layers of semiconductor materials, differing in dielectric constant or saturated carrier drift velocity or, in general, the ratio of the saturated drift velocity of the carrier charge to the material, increases significantly the thickness of the volume charge layer does not reduce the magnitude of the induced current, and hence the current gain of the transistor. This makes it possible to significantly reduce the specific capacity of the collector junction C | and, consequently, to increase the limiting frequency ito t, (due to a decrease in the delay time T | E PdCj, S is the base resistance), the maximum frequency of the power gain rtTa / fc power gain in the power E at the location with the increase in thickness, collector) south The volume charge layer of the gyup breaker is the breakdown voltage of the collector, and hence, the maximum net power of the transistor. Separate layers constituting the collector region can have both the same type of conductivity (e.g., p-type in a pnp transistor), and different types of conductivity (p- or p), provided that the collector layer adjacent to The base layer has the opposite type of conductivity. The impurity concentration in all layers of the collector should not be too high so that, at the working potential of the collector, the depleted area captured all the layers of the collector junction. Bipolar microwave transceiver containing the emitter, base and collector areas with metal electrodes and a combined collector junction layer, characterized in that, in order to increase the limit frequency of the current gain, the maximum frequency of the gain of power and reduce the specific collector capacitance , the combined layer of the collector junction is made of an even number of layers of two semiconductor materials arranged in an alternating sequence, and the drift velocity ratio is saturated and charge carriers to the dielectric constant in them satisfies the relation y / v, / / t, VCi, where e-.fr, is the dielectric constant of the layers; Vj jV. - saturation rates of charge carriers. Sources of Information Accepted in Examination 1. US Patent 3,826,956 l. 148-33.2, 1976. 2. Voltsit V.V. and others. Low-noise RF and microwave transistors. Semiconductor devices and their application, 1971 eup. 25