PHOTOELECTRIC PROPERTIES OF lONICALLY BOMBARDED SILICON 809 



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WAVELENGTH IN 



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 MICRONS 



Fig. 8 — Spectral response of the intermediate size cells at various bombarding 

 voltages. 



Electrodes 1|" in diameter of evaporated rhodium metal were applied in 

 like manner to each surface. Contact was made to the collector electrodes 

 by means of tin discs. Fig. 4 gives the forward and backward log voltage- 

 log current relation of this large cell. Without bombardment such an 

 arrangement shows ohmic conductivity so it is evident that the treat- 

 ment is responsible for the development of a potential barrier beneath 

 the surface. It is beheved from the high dark resistivity of the bom- 

 barded layer that the intrinsic properties of the silicon are developed 

 therein. Thus an intrinsic -p type potential barrier is produced similar 

 to a degree to the n-p junction. One would expect the depth of this bar- 

 rier to be related to the velocity of the ions. Consequently a study has 

 been made of the effect of ion velocity on the photoelectric properties. 



The photoelectric current at constant illuminance for a series of cells 

 prepared by bombardment with ions of different energies is shown in 

 Fig. 6. It is remarkable how quickly and completely the current sensi- 

 tivity saturates at approximately 500 volts. 



