COMBINED MEASUREMENTS ON ETCHED GERMANIUM SURFACES 1037 



10 



dY 

 drf" 4 



10-' 

 e 



10 



-4 



-2 



-1 1 



Y-ln\ 



Fig. 8 — Surface photo-voltage (change in contact potential in relation to 

 added carrier concentration). dY/d8 is shown plotted against F — In X. Dots: p- 

 fype; circles: 7i-type. Data from different runs are distinguished by modifications 

 to these symbols. The left-hand branches denote absolute magnitudes, since the 

 ratio is negative there. At the extreme left hand of the diagram, the fast states 

 near to the Fermi level are in good contact with the valence band: at the extreme 

 right hand, to the conduction band. The theoretical asymptotes (X~i to the left 

 and X to the right) are also indicated. 



temperature studied. This is the basic information which any theoreti- 

 cal treatment must explain. In the succeeding paper this matter is dis- 

 cussed from the point of view of the statistics of a distribution of fast 

 states, and information on the cross sections, as well as on the distribu- 

 tion itself, is derived from the data just presented. 



