34 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1956 



were made in the laboratory, the characteristics were remarkably uni- 

 form considering the ^•ariations usually encountered at such a stage of 

 development. It appears that diffusion process is sufficiently controllable 

 that the thickness of the base region can be reduced to half that of the 

 units described here. Therefore, with no change in the other design 

 parameters, outside of perhaps a different mounting, units with a 1000 

 mc/s cutoff frequency should be possible. 



ACKNOWLEDGMENT 



The author wishes to acknowledge the help of P. W. Foy and W. Wieg- 

 mann who aided in the construction of the transistors, D. E. Thomas who 

 designed the electrical equipment needed to characterize these units, 

 and J. Klein who helped with the electrical measurements. The numerical 

 evaluation of alpha for drift fields was done by Lillian Lee whose as- 

 sistance is gratefully acknowledged. 



REFERENCES 



1. C. S. Fuller, Phys. Rev., 86, pp. 136-137, 1952. 



2. J. Saby and W. C. Dunlap, Jr., Phys. Rev., 90, p. 630, 1953. 



3. W. Shocklej', private communication. 



4. H. Kromer, Archiv. der Elek. tlbertragung, 8, No. 5, pp. 223-228, 1954. 



5. R. A. Logan and M. Schwartz, Phys. Rev., 96, p. 46, 1954 



6. L. B. Valdes, Proc. I.R.E., 42, pp. 420-427, 1954. 



7. W. L. Bond and F. M. Smits, to be published. 



8. E. S. Rittner, Pnys. Rev., 94, p. 1161, 1954. 



9. W. M. Webster, Proc. I.R.E., 42, p. 914, 1954. 



10. J. M. Early, B.S.T.J., 33, pp. 517-533, 1954. 



