ABSTRACTS OF TECHNICAL ARTICLES 271 



Transport of Added Current Carriers in a Homogeneous Semicon- 

 ductor, Phys. Rev., 91, pp. 282-289, July lo, 1953 (iMonograph 2105). 



Takinji into account the thermal equilibrium minority carrier concentration 

 anil emplovinif the formulation which includes, as one of two fundamental 

 ecjuations, the continuity equation for added carrier concentration Ap, tliis 

 e(iuation is derived in a form which exhibits the ambi])olar natuie of the 

 difYusion, drift, and recombination mechanisms under electrical neutrality. 

 The geneial concentration-dei)en(lent diffusivity is given. The local drift 

 velocity of Ap has the direction of total current density in an n-tj^pe semi- 

 conductor and the reverse in a p-tji^e semiconductor, differing in general in 

 both magnitude and direction from the minoi'ity-carrier drift velocity. 

 Specifying a model for recombination fixes the dependence of a lifetime 

 function for Ap on Sp and the electron and hole mean lifetimes. Negative 

 Ap, or carrier depletion with electrical neutrality, may occur. For known 

 total current density, the continuity equation alone suffices, as for the case 

 of I Ap I small, for which the ec^uation is linear. A condition for this com- 

 parativeh' important case is derived, and theoretical relationships are gi\'en 

 with the aid of a parameter specifying the Fermi level, which determine for 

 germanium the minority carrier-Ap drift velocity ratio as well as the ambi- 

 polar diffusivity and group mobility in terms of resistivity and temperature. 



Vaughax, H. E., see W. A. Malthaner. 



VOGELSONG, J. H.^ 



Transistor Pulse Amplifier Using External Regeneration, I.R.E., 

 Proc, 41, pp. 1444 1450, Oct., 1953. 



Pulse-regenerative amplifier using a point-contact transistor has been op- 

 erated at a basic frequenc}' of 3 megacycles. To i)roduce regenerated pulses 

 with waveshapes which are practicalh' independent of the wa\-eshapes of 

 the input pulses, a germanium diode circuit has been used in conjunction 

 with an external feed-back path. This arrangement also provides for the 

 s^mchronization of the output pulses with a master clock. Transformer 

 coupling has been incorporated into the circuit to provide dc restoration. 



Walker, A. C.^ 



Hydrothermal Synthesis of Quartz Crystals, Am. Ceramic Soc, J., 

 36, pp. 250-256, Aug., 1953 (Monograph 2146). 



Research at the Bell Telephone liaboratories on the problem of growing 

 large single crystals of quartz has now i)rogressed to a point where it is 

 possible to grow crystals weighing more than 1 lb. each in a period of 60 

 daj's or less. Equipment now in use includes autoclaves 4 inches in inside 

 diameter and 4 ft. long, weighing about 1,150 11). each. In developing the 



1 Bell Telephone Laboratories. 



