|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1993 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1992 : ¥1,400,000 (Direct Cost : ¥1,400,000)
An ac- cold cathode type electron emitter was proposed at the same time by two research groups i.e. Muller's and the present author's groups.
This report is a part of the research to study the machanism of electron emission of this device and to find new material suitable to device for the better emission efficiency.
The mechanism of the electron emission of this device is thought to be as follows. The device is composed of an acceleration layr and an electron blocking (insulation) layr which are sandwiched between upper- and lower- film electrodes. As an ac-electric-field whose peak value exceeds the break-down field strength of the acceleration layr is applied to the device, electrons are injected from the negative upper-electrode, transferred, and stored at the surface between the acceleration- and the blocking-layrs. In the following half cycle, the polarization of the field is reversed and, as the field exceeds the break-down strength of the acceleration layr, the electrons reach to the upper-electrode with high energy and with multiplied numbers due to avalanche effect, resulting electron emission through the thin electrode into the vacuum.
This report describes the measurenment of stored charges and electron-emission currents of the devices with sulfide-, selenide-, organic-LB-film-, and oxide- acceleration layrs.
The results for the sulfide, selenide, and organic-LB devices shows that the stored charge is abruptly increased and the electron emission starts at an applied voltage corresponding to the break-down voltage of these layr, supporting the model mentioned above. The oxide-devices, however, show different feature from other three devices. The stored charge starts at rather low applied voltage and increased smoothly without showing any threshold voltage. The feature that the emission is decreased at high frequency is also different from the other devices. These features of the oxide-device as absorption current of insulators.