LOW-WORK-FUNCTION SURFACES FOR NEGATIVE-ELECTRON-AFFINITY PHOTOEMITTERS

The photoemission threshold of GaAsSingle Bond signCsSingle Bond signO is explained on the basis of a heterojunction model composed of GaAs and Cs 2O. The concepts involved in this model are generalized to an arbitrary heterojunction, leading to the result that it is, in principle, possible to obtain surfaces with work function lower than 0.5 eV. If deposited on an appropriate substrate, these surfaces offer the exciting possibility of highly efficient photoemission well into the infrared. A possible practical negative-electron-affinity photoemitter with efficient response to 1.4 μ is suggested. © 1969 The American Institute of Physics.