Fowler's hypothesis commonly used to interpret results of photoemission into the vacuum has been extended to deal with the problem of internal photoemission. This leads to the empirical relation $Y\propto {(E-E_t)}^2$ between the quantum efficiency $Y$ and the photon energy $E$, currently used to interpret hole photoemission experiments. $E_t$ is the threshold energy for photoemission. Various cases of internal electron and hole photoemission between metals and semiconductors are discussed.

• Received 17 May 1972

DOI:https://doi.org/10.1103/PhysRevB.7.3702