No abstract

Through use of an atomic force microscope (AFM), surface morphologies for SiN x and a-Si:H films were investigated. By controlling deposition conditions, very smooth films have been obtained. The thin film transistor (TFT) with smooth a-Si:H on smooth SiN x has both high mobility (1.0 cm2·V-1·s-1) and high stability at the same time. This high-performance TFT will make an important impact in application to high-pixel-density liquid crystal displays (LCDs), such as for use in workstations and high-definition television (HDTV).

Very High Frequency (VHF) has been applied to the plasma enhanced chemical vapour deposition (PECVD) of hydrogenated amorphous silicon nitride films (a-SiNx:H) to fabricate amorphous silicon (a-Si:H) thin film transistors (TFTs). Especially, the effect of the excitation frequency on the deposition rate and the film quality of a-SiNx.H deposited in a SiH4/NH3/N2 plasma has been investigated. The films were prepared by VHF (40 MHz and 60 MHz) and HF (13.56 MHz) plasma enhanced CVD.The optical bandgap, the hydrogen content, the Si-H/N-H ratio and TFT mobility for films deposited in VHF plasma did not change significantly with the increase in deposition rate up to 300 nm/min. Internal stress could be constrained to acceptable levels at very high deposition rates. In contrast, the film quality deteriorated with an increase of the deposition rate in HF plasma. There seems to be a parallel relation between the optical emission intensity and the deposition rate which depends on the excitation frequency.

Characteristic dark domains are observed around the tips of electrodes in in-plane switching-mode liquid crystal displays. In these domains, the liquid crystal molecules rotate in the reverse direction because of the radially distorted electric field. We found that these domains extend toward the central area when a higher voltage is applied. This article discusses these reverse-rotational domains.

No abstract