Virtual image‐ and field‐induced electronic states

Abstract

The inverse photoemission technique enables us to examine the unoccupied s u rface states on semiconductors and on metals /1,2/. Of particular interest are the so-called image states resulting f r o m the long-range p a r t of the surface potential. These high energy states, recently extensively studied on metal s u rfaces /3,4/, are tied to the vacuum level Vo. Their wave functions have the