Ion beam irradiation effects on a novolac positive-tone photoresist and its application to micron-size field emitters have been investigated. Irradiation of Ar and P ions was examined. The electrical resistivity of the photoresist film is found to decrease after Ar ion implantation at doses on the order of 1016 cm-2. Baking of the photoresist prior to irradiation at a high temperature is preferred to produce electrical conductivity. P ions show weaker effects than Ar ions. Raman spectroscopy shows that carbon-carbon bonds such as the graphite bond are produced due to ion bombardment. The field emission of electrons is observed from emitters made of the ion-irradiated photoresist. The emission current is shown to be fairly stable when it is compared with an emission characteristic of synthesized diamond. Fabrication of field emitter arrays using a mold technique is demonstrated. The field emitter array shows emission at a current level of about 40 µA.

The role of electric field in metal-induced lateral crystallization (MILC) of amorphous Si (a-Si) under limited Ni-supply condition has been investigated. The nominal lateral-growth rate was increased from 3.6 µm/h (no-electric field) to 23 µm/h at the positive electrode side and reduced to 2.8 µm/h at the negative electrode side in presence of the electric field of 20 V/cm. However, spontaneously nucleated needle-like Si crystals were observed in the enhanced positive electrode side, which have been found to be independent of the MILC. Further investigation under the condition where Ni in the supply region was removed on the way of crystallization revealed that the electric field enhanced crystallization greatly reduced. These results indicate that the electric field does not enhance the MILC growth but enhances the diffusion of Ni in a-Si which takes place prior to the MILC growth.

We experimentally investigated terahertz photomixing operation at room temperature in an InGaP/InGaAs/ GaAs two-dimensional plasmon-resonant photomixer incorporating grating-bicoupled dual-gate structure. Photoelectrons drifting into a high-density plasmon cavity grating from an adjacent low-density one extensively excite the plasmon resonance, resulting in emission of terahertz radiation. A vertical cavity formed between the two-dimensional plasmon grating plane and an indium-tin-oxide mirror at the back surface gains the radiation. Self-oscillation initially at around 4.5 THz excited by a dc-photo carrier component was reinforced by the photomixed differential-frequency excitation at 4.0 and 5.0 THz. This indicates a possibility of injection-locked oscillation of the photomixer in the terahertz frequency band.

This paper describes the operation and the test results of a novel comparator, called a differential voltage (ΔV) comparator, which detects the difference between two input signal voltages. This comparator utilizes variable threshold voltage inverters (VT-INVs) which can change a logic threshold continuously using a variable channel size MOSFETs (VS-MOSs). The circuit configuration is very simple, and has the potential to achieve high integration and low power consumption in mixed signal system LSIs.