PHOTOELECTRK' I'ROPKRTIKS OF lONICALLY HOMBAKDKD SIIJCOX <S()3 



silicon. The material of opposite type was named p-type. Material of 

 the n-type is now known to derive its electrical properties from tiie 

 presence in th(^ crystal lattice of eUn'tron donor impurities, for example 

 phosphorus, while p-ty\)o derives its electrical pi'operties from the pres- 

 ence of electi'on acceptor impurities, such as boron. In this paper some 

 of the results of investigations of the natural barrier are reported ; how- 

 ever, the jihotovoltaic properties of induced barriers obtained by the 

 ionic bombardment of p-type silicon will be given more detail treatment. 



EARLY RESULTS 



The approximate location of the natural barrier found in earl}^ melts 

 is shown in Fig. 1. The barrier was generally located in the melt per- 

 pendicular to the axis of the melting crucible or more accurately to the 

 direction of the temperature gradient. Plates and rods containing sec- 

 tions of the photoactive barrier, Fig. la, were cut from the melt and 

 mounted on convenient supports for laboratory tests. Fig. Ic shows a 

 magnified section of one of these barriers. 



Fig. 1 — (a) Drawing of melt showing position of photovoltaic harrier and i)hoto 

 cells with natural l)arrier. (b) Drawing of melt showing surface type jihoto cell 

 made from natural harrier, (c) Magnified, etched section of slowly cooled silicon 

 showing the transition between p and n silicon forming the barrier which consists 

 of intermeshed striae of these two varieties. 



