The Free On-line Dictionary of Computing (30 December 2018):

electron model

    A model of semiconductor behaviour in which
   donors contribute the charge of an electron, and
   acceptors contribute a space for same, in effect
   contributing a fictional positive charge of similiar
   magnitude.  Physicists use the electron model.  Some
   language theorists consider language and the electron to be
   models in themselves.

   Contrast hole model.

   (1995-10-06)