An important contribution, with the British physicist Fowler in 1928, was to establish the correct physical explanation of the physical phenomenon now called field electron emission (FE). They established that electron emission occurred by a form of wave-mechanical tunneling, now called Fowler–Nordheim (FN) tunnelling, and, with the help of the assumption that electrons in metals obeyed Fermi-Dirac statistics, derived an (approximate) emission equation. Over time, this equation has been developed into a family of approximate equations (offering different degrees of approximation to reality, when describing FE from bulk metals), known as Fowler-Nordheim-type equations.
FN tunneling was the first effect in physics to be firmly identified as due to wave-mechanical tunneling, in the early days of quantum mechanics. The original FN-type equation was one of the first to use Fermi-Dirac statistics to explain an experimental phenomenon involving electrons in metals, and its success greatly helped to establish modern electron band theory.
FE has had many significant practical applications (see main article on FE.).