Work Function and Other Emission Measurements

Abstract

A variety of methods have been employed over many years for the experimental determination of the work function of metal and semiconductor surfaces. There exist, at the present time, a number of review articles relating to work function measurements on single-crystal planes (Riviere, 1969; Fomenko, 1966; Haas and Thomas, 1972; Swanson and Bell, 1973; Holzl and Shulte, 1979). Most of these review articles contain extensive lists of the available experimental data along with a detailed description of various methods of measurement. Some of these methods are based on the formulas for field emission and thermionic emission given in Chapter 1. We shall describe, very briefly, some of these methods. We are concerned only with measurements taken from single-crystal planes of metals and under conditions such that space-charge effects are negligible. Some aspects of electron emission from adsorbate-covered metal surfaces will be discussed in Chapter 6. We note that although quite often the same methods are used for measuring the work function and other “emission parameters” of adsorbate covered surfaces as for clean uniform surfaces, a quantitative analysis of the data in the former case involves additional assumptions (if the same formulas are to be used), which may or may not be justified. We emphasize that the formulas in Chapter 1 apply only to emission from plane and uniform metal surfaces.