Field Emission

III-V-Halbleiter Feldemissions-Sensoren und Mikrowellenquellen

Prof. Dr. Eng. Dr. h. c. mult H. L. Hartnagel

Prof. Dr. D. Pavlidis

Dr.-Ing. O. Yilmazoglu

Band diagram of a semiconductor field-emitter under biasing.
Band diagram of a semiconductor field-emitter under biasing.

Field emission is a quantum mechanical tunneling process and is described by the Fowler-Nordheim equation. This cold emission is ideal for temperature independent and radiation hard current sources. Main application fields are in flat panel displays, sensors, x-ray sources, scanning electron microscopes, mass spectrometers and microwave amplifiers.

Field emitter charakteristics:

  • Field emission starts for E > 10^7V/cm
  • High current density: J(E) = A·E^2 Phi exp^(-B Phi^1.5 /E)
  • Strong nonlinear current-voltage characteristic
  • Very short switchung time (t <ns)
Field emitter for vibration sensors
Field emitter for vibration sensors

Field emission is strongly non-linear with respect to the applied electrical field. For cantilever or bridge structures one can easily modify this electrical field by changing the distance between anode and cathode. The current density increases 400 times when the applied electrical field increases 25% (@2x10^7 V/cm)

In order to decrease the threshold voltage and improve the stqability of the emitter special coating layers can be used. In this connection DLC has proven to be a promising candidate. Beside reducing the threshold voltage NDR regions could, as shown in the characteristics, obtained due to resonant tunneling effects. These NDR can be used for microwave generation in a resonator.

Veröffentlichungen / Relevant Publications:

  • V. Litovchenko, A. Evtukh, O. Yilmazoglu, K. Mutamba, H.L. Hartnagel, D. Pavlidis: Gunn effect in field-emission phenomena. J. Appl. Phys., Vol. 97, 044911, 2005.
  • V. Litovchenko, A. Evtukh, Yu. Kryuchenko, N. Goncharuk, O. Yilmazoglu, K. Mutamba, H.L. Hartnagel, D. Pavlidis: Quantum-size resonance tunneling in the field emission phenomenon. Appl. Phys., Vol. 96, 2004, pp. 867-876.
  • H. Mimura, O. Yilmazoglu, H. Shimawaki, K. Yokoo, K. Mutamba, H. Hartnagel: Emission Characteristics of a Gallium Arsenide Wedge Emitter Monolithically Fabricated with an Air Bridge and a Cantilever Anode. JVST B, Vol. 21, No. 1, 2003, pp.471-473.
  • A. Evtukh, H. Hartnagel, V. Litovchenko, O. Yilmazoglu: Two Mechanisms of Negative Dinamic Conductivity and Generation of Oscillation in Field-Emission Structures. Material Science and Engineering A, Vol. 353, 2003, pp.27-35.
  • V.G. Litovchenko, A.A. Evtukh, Yu.M. Litvin, N.M. Goncharuk, H. Hartnagel, O. Yilmazoglu: Peculiarities of the Electron Field Emission from Quantum-Size Structures. Applied Surface Science, Vol. 215, 2003, pp.160-168.
  • O. Yilmazoglu, H. Mimura, K. Mutamba, H.L. Hartnagel, K. Okamura, H. Shimawaki and K. Yokoo: Generation of Modulation Beam with GaAs Field-Emitter Structures. Proceedings IVEC 2001, Nordwijk, The Netherland, 2001, pp.243-246.