AVS 45th International Symposium
    Electronic Materials and Processing Division Monday Sessions
       Session EM-MoM

Paper EM-MoM9
Field Emission Energy Distributions from Silicon Field Emitter Arrays

Monday, November 2, 1998, 11:00 am, Room 316

Session: Processing for Advanced Technology
Presenter: J.L. Shaw, Naval Research Laboratory
Authors: J.L. Shaw, Naval Research Laboratory
H.F. Gray, Naval Research Laboratory
K. Hobart, Naval Research Laboratory
Correspondent: Click to Email
A great deal of work on field emitter array (FEA) surface coatings, treatments, and "conditioning" effects has been has been reported in hopes of improving the maximum current, robustness, and transconductance. However, the typical current-voltage diagnostic technique has limited utility in understanding the effects of such treatments. Field enhancement and work function effects are difficult to separate using I-V measurements and assuming the classical Fowler-Nordheim theory. Furthermore, the I-V characteristics typically vary with time and emission even in UHV. To better understand the emission process, we have measured FEA emission energy spectra. Our equipment includes a hemispherical analyzer and allows in-situ wafer probing and simultaneous I-V characterization. The spectra we obtain include structure at lower energies than reported from single, macroscopic, clean silicon tips. Since the emission energy relative to the bulk Fermi level represents a loss, such spectra are of considerable interest. The spectra change as a function of emission current, conditioning, and processing. In some cases we find energy losses in excess of 10 volts. Such losses may explain why failures can occur at emission levels below 1uA, even though calculations (that assume straightforward Joule and Nottingham heating) predict no temperature increase at emission currents below 100uA. Our measurements suggest that both the emission current and dissipated energy can be strongly influenced by the presence of surface states. Thus detecting such effects is likely to prove useful in improving FEA emission uniformity and total current density.