Generalized electron emission model for field, thermal, and photoemission

Analysis of electron emission from photocathodes, field emitters under extreme fields, or thermionic emitters operated at reduced temperature, utilize thermionic (Richardson) or field emission (Fowler-Nordheim) approximations which become inaccurate for such atypical conditions. The computational overhead of advanced numerical transport models make them ill-suited for data analysis or simulations of extended areas of photocathode and thermionic emitters, or for nonplanar field emitters. In this letter, an analytic thermal-field emission equation is given for which the Fowler-Nordheim and Richardson-Laue-Dushman equations are asymptotic limits. The methodology can analytically address "warm" field and "cool" thermionic emission, photoemission, and electron transport between interfaces (e.g., Schottky barriers). The approximations developed are compared to an exact evaluation (the modified airy function approach). (C) 2002 American Institute of Physics.