The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Fabrication and characterization of gated silicon field emission micro triodes
Author:	Liu, Nanchou
View Online:	njit-etd1992-027 (xiii, 115 pages ~ 4.0 MB pdf)
Department:	Department of Electrical and Computer Engineering
Degree:	Doctor of Philosophy
Program:	Electrical Engineering
Document Type:	Dissertation
Advisory Committee:	Marcus, Robert Boris (Committee chair) Chin, Ken K. (Committee member) Cornely, Roy H. (Committee member) Carr, William N. (Committee member) Kosonocky, Walter F. (Committee member)
Date:	1992-10
Keywords:	Field emission. Silicon. Triodes.
Availability:	Unrestricted
Abstract:	This dissertation describes the fabrication technology and characterization of a gated silicon field emission micro triode that is a novel electron tunneling device for generating electron emission into a vacuum. Conic (point) and wedge field emitter structures with nm-scale radii were fabricated in silicon and GaAs by etching, MOCVD and dry oxidation. A new self-aligned process was developed for fabrication of vertical field emission triodes. This process allows control of gate opening to less than 0.5 μm diameter without the need of electron-beam writing. It also provides a planar gate electrode and a thick dielectric layer for reduction of the gate-cathode capacitance. Gated silicon field emission triodes, with silicon resistivity of 0.005 - 0.02 Ω-cm were studied. Gate and collector currents were measured in a vacuum of 2 x 10-8 Corr, and current-voltage (I vs. V), current-time (I vs. t), Fowler-Nordheim (I/V2 vs. 1/V), and triode characteristics were determined. The data showed that the electron emission followed Fowler-Nordheim behavior. Single emitters had turn-on gate to cathode voltages (V) above 25 volts (typically 50 - 90 volts) and reproducible emission currents were measured in the range 5 pA - 1 μA. Emitting areas of 1.0x10-16 -1.5x10-11 cm2 and field conversion factors α/r (where electric field = V α/r) of 3x105 - 8x105 cm-1 were calculated. Temporal fluctuations in emission current of 10%, 16%, and 40% were found for emission currents of 0.35 nA, 50 nA, and 0.5 μA, respectively. The triode characteristics showed an Ig/Ic ratio of 0.25% and higher. Transconductances were found to be 3 x10-8 mhos/tip. Leakage characteristics of various dielectric materials used in the new self-aligned process (thermal oxide, CVD oxide, polyimide and spin-on-glass) were measured and evaluated. Electrostatic discharge and other device failure mechanisms have been observed and explained.