A simple derivation of field-effect transistor characteristics
In the conventional treatment of the field effect 
transistor, the first step is the specification 
of an impurity profile that describes the 
nature of the gate-channel contact. Solutions 
for the static and small-signal characteristics 
are then valid only for the particular 
impurity profile chosen, and must be repeated 
from the beginning for different 
structures. 
 
The purpose of this communication is to 
present a simple, though approximate, 
development of the characteristics of an 
FET without specifying the detailed nature 
of the structure. The charge-control approach is used, and it is shown that in the pinch-off region the relation between the drain current and the gate-source voltage is 
approximately square law. The results are 
applicable to all gate-channel structures, 
including the insulated gate types.
Approximation of junction field-effect transistor characteristics by a hyperbolic function
To analyze nonlinear circuits using the junction field-effect transistor (JFET), a new empirical equation is proposed to relate drain current to drain-source and gate-source voltages. This equation is a simpler form than the Shockley equations, and requires only drain characteristics to evaluate the constant /spl alpha/ in this equation. Good agreement is obtained between the predicted and experimental results.
Some properties and applications of space-charge-limited currents in insulating crystals
The mechanisms of current through insulators in the presence of surface potential barriers and electron traps are discussed, and the simplified theory of space-charge-limited current through insulating solids is described. The steady-state equations for one-dimensional single-carrier current are derived and approximate solutions are given; theoretical current/voltage characteristics are calculated and indicate that large currents could flow and that their characteristics could be utilized in practical devices. The continuity equations for time-varying current are derived for the case when electron transit times and trapping relaxation times are both significant.Experiments are described which have demonstrated some of the predicted characteristics of space-charge-limited current; in particular a threshold voltage for current, a square-law dependence of current upon applied voltage, and rectification have been observed. The currents are of practical magnitudes; steady and reproducible current densities of several amperes per square centimetre have been drawn through insulating crystals of cadmium sulphide at room temperature with a few volts applied. Measurements with microsecond pulses have shown that there is no detectable delay by the crystal in responding to a pulse rise or fall time of the order of 0.1 microsec; there seems no fundamental reason why response times as short as 0.1 milli-microsec should not be expected.It is apparent that many new types of solid-state device may be developed by exploiting current in insulators. Some possible applications are discussed, including a dielectric triode which should combine the high input impedance of the vacuum triode with the high current output of the transistor and have a gain-bandwidth product as great as that of either device. The technical difficulties involved in developing space-charge-limited dielectric devices seem no greater than those successfully overcome in developing presently available semiconductor devices.