| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 81 === Presented here is a new numerical siumlation tool for gated
field emission triode(GFET) considering space charge effect and
temperature effect. The mesh structure used in our simulation
tool is very flexible, about 1 A near the tip and 1 um near
anode. This kind of mesh structure can be used to accurately
estimat the field at tip peak without using field enhancement
factor and the CPU time is greatly reduced. In addition, the
imporant of the number of meshes in obtaining correct
simulation result is discussed and verified. The strong
geometrical dependence of tip emission for GFET is usually
observed in most simulation programs. However, we have shown
that gate thickness can be optimized to reduce the leakage
current between gate and cathode. Simulation including space
charge effect has resulted in the speculation of the
underestimation of area of GFET array. This can be used to
explain the controversy of the value of the on-set voltage. And
the space charge effect lowering the tip emitting current is
observed, too. Finally, the thermal stability of GFET is
discussed. If Nottingham effect is considered, the knowledge of
the Eiffel-Tower shape tip is the most stable structure is
questioned. Our results show that Nottingham effect is the
dominant factor to heat tip other than Joule heating effect as
some papers suggested. In addition, the influence of tip half
angle and work function on thermal characteristics of GFET is
discussed.
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