Analysis of a photon assisted field emission device

A field emitter array held at the threshold of emission by a dc gate potent ial from which current pulses are triggered by the application of a laser p ulse on the backside of the semiconductor may produce electron bunches ("de nsity modulation") at gigahertz frequencies. We develop an analytical model of such optically controlled emission from a silicon tip using a modified Wentzel-Kramers-Brillouin and Airy function approach to solving Schrodinger 's equation. Band bending and an approximation to the exchange-correlation effects on the image charge potential are included for an array of hyperbol ic emitters with a distribution in tip radii and work function. For a simpl e relationship between the incident photon flux and the resultant electron density at the emission site, an estimation of the tunneling current is mad e. An example of the operation and design of such a photon-assisted field e mission device is given. (C) 2000 American Institute of Physics. [S0003-695 1(00)00730-0].