PROPERTIES OF IONIC BOMBARDED SILICON 121 



content. In tlie case of bombarded silicon the effect is much less. More 

 particularly it is possible to contaminate •.silicon with impurities such 

 as boron to the point where its rectifying properties are almost com- 

 pletely lost and by bombardment it is possible to convert the crystal 

 into a very useful rectifier. It is possible to produce results similar to 

 the above by exposing the crystal to radioacti^^e polonium. Bombarded 

 materials appear to be relatively stable. 



The writer wishes to express his appreciation of the encouragement 

 and help of Dr. G. C. South worth in the preparation of this paper, to 

 A. J. jNIohr, Jr., for his able assistance in the experimental work, and 

 to numerous associates in Bell Telephone Laboratories for their assist- 

 ance in preparing materials and in making special tests for which the 

 author was not adequately equipped. 



