PRESENT STATUS OF TRANSISTOR DEVELOPMENT 413 



tact devices with new ranges of performance are indicated. Even more 

 importantly, new p-n junction devices have been built in the laboratory 

 anil those junction devices have indicated an extension in several per- 

 formance characteristics. 



f — By having interchangeable and reliahle devices with a wider range 

 of characteristics, it has become possil)le to carry on exploratory circuit 

 and sj'stem applications on a more realistic basis. Such applications 

 effort is, in turn, stimulating the development of new devices towards 

 new characteristics needed by these circuit and system studies. 



It is tlie purpose of the remainder of tliis paper to give an over all but 

 brief summary of recent progress made at Bell Telephone Laboratories 

 in reducing the above-mentioned limitations on reproducibility, relia- 

 bility and performance. Since a fair number of types of devices are cur- 

 rently under development, each with different characteristics to be op- 

 timized, the data will be presented as a sort of montage of characteristics 

 of several different types of devices. It is not to be inferred that any one 

 type of transistor combines all of the virtues any more than such a 

 situation exists in the electron tube art. Moreover, it will be impossible 

 in a paper of practical length to present complete detailed characteristics 

 on all or even several of these devices under development; nor would 

 it be appropriate since most of these data are on devices currently under 

 development. Rather, what is desired, is a summary of progress across 

 the board to give the reader an integrated and up-to-date picture of the 

 current state of transistor electronics. 



REPRODUCIBILITY STATUS 



Description of Transistors 



Before quantitative data comparing the characteristics of past with 

 present transistors are presented, it will be useful to briefly review 

 physical descriptions of the various types of transistors to be discussed. 

 Fig. 1 shows a cutaway view of the now familiar point-contact cartridge 

 type transistor. All of the early transistors were of this general construc- 

 tion and the characteristics of a particular one, called the Type A\ will 

 be used as a reference against which to measure results now obtainable 

 with new types under current development. Fig. 2 is a semi-schematic 

 picture of the physical operation of such a device. Pressing down upon 

 the surface of a small die of ?i-type germanium are two rectifying metal 

 electrodes, one labelled E for emitter, the other C for collector. A third 

 electrode, the base, is a large area ohmic contact to the underside of 

 the die of germanium. The emitter and collector electrodes obtain their 



