Development of an active-matrix "HEED" cold cathode and its application to an image sensor
For practical advantages of the HEED (high-efficiency electron emission device) such as a low driving voltage, a high emission current density, especially application to an ultra high sensitive compact image sensor can be expected. A prototype active-matrix HEED image sensor integrated with scanning driver circuits was developed with a HARP (high-gain avalanche rushing amorphous photoconductor) target. It was demonstrated that the prototype 256 times 192 pixels active-matrix HEED array operates well as an effective probe for high-resolution image pickup under dim lighting. The possibility of the active-matrix HEED for development of next-generation image sensor with ultra high sensitivity and high definition was concluded in this report
High Efficiency Electron-Emission in Pt/SiOx/Si/Al Structure
A high efficiency electro-emission device (HEED) has been developed with a structure of Pt/SiOx /Si/Al on a thermally-oxidized Si substrate. The thicknesses of the SiOx and Si films were 400 nm and 5 µ m, respectively. Electron emission characteristics of the HEED are reported. It was found that the HEED has an electron-emission efficiency as high as 28% and a high brightness of 80 kcd/m2 using phosphor ZnS:Cu,Al. This high electron-emission efficiency was obtained in a range of applied voltage in which negative resistance occurred.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.