Developments in Ceramic Materials Research

Field Emission Display on Ceramic 253
Figure 7. Schematic diagram of the field emission characterisation setup.
Another Keithley source meter model 2410, with an ability to supply a higher voltage up
to 1.1 kV, was used to power the phosphor screen anode referenced to the common ground.
The source meter 2410 monitors the emission electron current collected by the phosphor
screen anode. Both the Keithley source meters are programmable. They communicated
automatically to the central control system - a personal computer (PC) via a General Purpose
Interface Bus (GPIB). The entire automatic control and data acquisition between the PC and
the two source meters were achieved through a specific software control program, designed
using the instrument oriented LabVIEW package (National Instruments).
Ultra high vacuum condition can be achieved quicker by baking the vacuum test chamber
at an elevated temperature in the range of 150°C~200°C. A base pressure of 5×10 -10 mbar was
acquirable after an overnight bake out, followed by cooling down to room temperature.
Electrical Characteristic Study: Experimental Data Results
One basic electrical characterisation of the micro field emitters is to obtain the emission
electron current as a function of the gate voltage curve (I-V curve). This was performed by
ramping up the gate electrode potential voltage from 0 up to a certain value, normally less
than 200 V, while measuring the emission electron current from the field emitter cathode. To
enhance the efficiency of emitted electrons to impinge the phosphor screen anode, the emitted
electrons are attracted toward the anode electrode under an action of a strong static electric
field. Electrons collided into the anode, where a current flow was detected through the
electrical circuit. Another important I-V curve to characterise the micro field emitters is to
obtain a curve of the leakage current versus the gate voltage. This I-V curve reveals the
quality of the SiO2 dielectric layer, which separates the gate electrode and the cathode. Here,
the leakage current was acquired by the Keithley source meter 2400 in the experiments. A
specific emission current and leakage current via gate voltage characteristics obtained from a
micro field emitter array is illustrated in Figure 8 (a).