THE BELL SYSTEM 



TECHNICAL JOURNAL 



V o L u M E X X X I I I M A Y 1 9 5 4 n u M b e R 3 



Copyright, 1954, American Telephone and Telegraph Company 



P-N-I-P and N-P-I-N Junction Transistor 



Triodes 



By J. M. EARLY 



(Manuscript received March 18, 1954) 



Theory indicates that the useful frequency range of junction transistor 

 riodes may he extended by a factor of ten by a new structure, the p-n-i-p, 

 which uses a thick collector depletion layer of intrinsic {i-type) semiconduc- 

 tor to reduce greatly the collector capacitance and to increase the collector 

 breakdown voltage. This structure will permit simultaneous achievement of 

 high alpha cutoff frequency, low ohmic base resistance, low collector capac- 

 itance, and high collector breakdown voltage. Because of the high breakdown 

 voltages and larger areas per unit capacitance, permissible power dissipa- 

 tions appear much larger than for other high frequency junction types. The- 

 oretical calculations indicate that oscillations at frequencies as high as 3,000 

 mcps may he possible. 



Early exploratory models have verified the basic theory. Progress toward 

 initial design objectives has been encouraging. In general, the observed per- 

 formance has been consistent with the materials used and the structure 

 achieved. The highest frequency of oscillation obtained to date is 95 mcps. 

 Better performance is expected as technical control of materials and struc- 

 tures is improved. 



In the five years since the announcement of the junction transistor 

 by Shockley, great steps have been made in extending its useful fre- 

 quency range and its power-handling capacity. Recent developments, 

 particularly those which have increased the f requeue j^ range,"" "" ^ have 

 brought the performance of practical devices close to ultimate limits 



517 



