An important contribution, with the British physicist Ralph H. Fowler in 1928, was to establish the correct physical explanation of the physical phenomenon now called field electron emission. They established that electron emission occurred by a form of wave-mechanical tunneling, now called Fowler–Nordheim tunneling, 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 field emission from bulk metals), known as Fowler–Nordheim-type equations.
