Field Emission from Semiconductors

Abstract

The interest in field emission (FE) from semiconductors is stimulated by the following unique features of this process:

• 1. FE provides a source of valuable information on the physics of solid state surfaces. FE and ion emission microscopy, which enable visualization of solid state surfaces with high resolution and magnification yield data on a number of important characteristics of the surface such as the work function, ionization potential of surface atoms, electron affinity, surface tension, evaporation energy of the surface atoms, and activation energies for surface transport processes. Knowledge gained by these techniques in studies of surface phenomena on metals are widely known.^{13, 14, 19, 23, 29, 285} Initially the application of these techniques to semiconductors presented many problems due to the difficulty of cleaning the surface of a semiconductor emitter and obtaining a symmetric emission image. In this chapter the issue of semiconductor tip surface cleaning is given special consideration.

• 2. Distinct from metals, a semiconductor offers numerous ways of varying the characteristics of the emission process by control of carrier concentration in the emitter bulk, thus making unique electron devices possible. In recent years a number of ideas have been generated which might lead to new systems in vacuum electronics. It appears possible to have a limited carrier concentration in the near-surface region of a semiconductor and control the FE process by generating or injecting carriers into this region.

• 3. Application of semiconductors in vacuum microelectronics is aided by the fact that for some semiconductor materials, such as Si, the basic technology of fabricating complex structures has been developed.