248 BELL SYSTEM TECHNICAL JOURNAL 



In reference 1, the characteristics of an experimental transistor were shown 

 by giving the constant voltage contours on a plot in which the independent 

 variables le and Ic are plotted along the coordinate axes. 



In the following we give further characteristics, and show in a general 

 way how they depend on the spacing between the points, on the tempera- 

 ture, and on the frequency. The data were taken mainly on experimental 

 setups on a laboratory bench, and are not to be taken as necessarily typical 

 of the characteristics of finished units. They do indicate in a general way 

 the type of results which can be obtained. Characteristics of units made in 

 pilot production have been given elsewhere.^ 



The data plotted in reference 1 were taken on a transitor made with phos- 

 phor bronze points on a surface which was oxidized and on which potential 

 probe tests gave evidence for considerable surface conductivity. The col- 

 lector resistance is small in units prepared in this way. In Fig. 3 are shown 

 the characteristics of a unit^^ in which the surface was prepared in a differ- 

 ent manner. The surface was ground and etched in the usual way", but 

 was not subjected to the oxidation treatment. Phosphor bronze contact 

 points made from 5 mil wire were used. The collector was electrically 

 formed by passing large currents in the reverse direction. This reduced 

 the resistance of the collector in the reverse direction, improving the transis- 

 tor action. However, it remained considerably higher than that of the 

 collector on the oxidized surface. 



While there are many ways of plotting the data, we have chosen to give 

 the collector voltage, Vc, as a function of the collector current, Ic, with the 

 emitter current, le, taken as a parameter. This plot shows in a direct 

 manner the mfluence of the emitter current on the current-voltage char- 

 acteristic of the collector. The curve corresponding to /« = is just the 

 normal reverse characteristic of the collector as a rectifier. The other 

 curves show how the characteristic shifts to the right, corresponding to 

 larger collector currents, with increase in emitter current. It may be noted 

 that the change in collector current for fixed collector voltage is larger than 

 the change in emitter current. The current amplification factor, a, defined 

 by 



a = — (5/c/<9/e)vv = const. (2-1) 



is between 2 and 3 throughout most of the plot. 



The dotted lines on Fig. 3 correspond to constant values of the emitter 

 voltage, Ve- By interpolating between the contours, all four variables 

 corresponding to a given operating point may be obtained. The Ve con- 

 tours reach a maximum for /« about 0.7 ma. and have a negative slope 

 beyond. To the left of the maximum, V, increases with L as one follows 

 along a line corresponding to Vc = const. To the right, Ve decreases as 



