Papers by Keyword: Fowler-Nordheim Plot

Abstract: A simple method for fabricating lateral Si diodes with various gap widths were designed using the special properties of anisotropic TMAH wet etching and local anodic oxidation. The electrical performance of lateral diode was characterized using an HP4156c semiconductor parameter analyzer (SPA300HV, Agilent) at room temperature in a vacuum environment lower than 10^-8 Torr. The emission current from the silicon emitter cathode was measured as a function of the applied anode voltage. The effect of changing the anode-cathode gap was observed in the I-V characteristics, with a distinct reduction in the device turn-on with a decrease in the gap. For narrowed nanogaps from 55 nm to 35 nm, the turn-on voltage was decreased from 21 V to 16 V. Values of field enhancement factor β and emitting area A for different gap width were measured using Fowler-Nordheim plot. Our results indicate that β reduces and emitting area increases with increasing of gap width.

Abstract: Field emission from Al-doped ZnO nanostrcutures has been investigated in planar diode configuration under ultra high vacuum conditions. The Al-doped ZnO nanostructures were synthesized by co-precipitation method with varying aluminium concentrations. The as- synthesized product was characterized by x-ray diffraction, scanning electron microscope and energy dispersive x-ray analysis. The threshold field required to draw a current density of ~ 1 μA/cm2 was observed to be ~ 2.0 V/μm and ~ 2.3 V/μm for Al-doped ZnO nanostructures synthesized with aluminium concentrations of 1% and 3%, respectively. The Fowler- Nordheim (F-N) plots for both the specimens exhibit non-linear behaviour, which is observed to be specimen dependent. The non-linearity observed in the F-N plots has been interpreted on the basis of the theory of electron emission from semiconductor emitters. The field enhancement factors, estimated from the slope of the F-N plots, are found to be ~ 9.3 x 103 and 3.9 x 103 for 1% and 3% Al-doped ZnO emitters, respectively. The high values of the field enhancement factor suggest that the emission is from the nanostructures. The emission current stability measured at the preset value of ~ 2 μA over a period of more than three hours is found to be fairly stable. The results indicate use of Al-doped ZnO nanostructures as promising emitters for field emission based devices.

Abstract: Recently, the micro-column has been intensively studied as a potential candidate for next-generation lithography with high-throughput capability. The micro-column has a simple structure with an electron emitter, micro-lenses, a double octupole deflector, and an Einzel lens. The structure and performance of the micro-column are dependent on the characteristics of the electron emitter. The electron emitter should have several prerequisites such as stable emission of electrons, high brightness and long lifetime. It is also necessary for the emitted electrons to have sufficiently low kinetic energy, which can be achieved by using a very sharp emission tip. In this work, we made an extremely sharp tip by electro-chemically etching the tungsten wire in 10 % KOH solution. From the Fowler-Nordheim plot, the effective radius of the tip was found to be as small as ~12 nm, which is consistent with the value measured by SEM. We also discovered that the stability of emission can be enhanced very much through thermal treatment of the tip end by irradiating the Nd:YAG laser pulse