Influences of silicon nitride (SiNx) films on the electrical performances of hydrogenated amorphous silicon thin film transistors (a-Si : H TFTs) are studied. Relatively low temperature (200 °C) SiNx films are prepared by plasma enhanced chemical vapour deposition at different radio-frequency powers. Results indicate that the SiNx films at a radio-frequency power of 340 W (Power density = 1.96 × 10−1 W cm−2) are near-stoichiometric and have better interface quality. Therefore, a-Si : H TFTs with this SiNx gate dielectric layer have a high field effect mobility and sustain the bias stress. The field effect mobility is 0.59 cm2 V−1 s−1 and the threshold voltage shift after a constant voltage stress (CVS) for 2.8 h is 3.18 V. The electrical degradation mechanism of a-Si : H TFTs is studied from the capacitance–voltage measurement. The degradation of the a-Si : H TFT after CVS is due to the defect generation in the SiNx gate dielectric and a-Si : H active layers. However, when the surface roughness of the SiNx film is poor, the degradation from the a-Si : H/SiNx interface is predominated. Therefore, if the SiNx film is used as a gate dielectric layer to fabricate a-Si : H TFTs, the surface roughness and chemical composition of the SiNx film should be considered simultaneously.

physical and mechanical properties, is one of the most important materials used in the mechanical, telecommunication and optoelectronic industty. However, high hardness value and extreme briuleness have made diamond a yery dicacult material to be machined by conventional rnechanicat grinding and po]ishing. In the present study, thc microwave CVD method was employed to produce epitaxial diamond films on silicon single crystal. Reactive ion etching (RIE), laser ablation and thermo-chemical polishing experiments were then conducted on the obtained diamond fiIms, The underlying material removal mechanisms, microstructure ofthe machinedsurface and related machining conditions were also investigated. Lt was tbund that during the laser ablation, peaks of the diamond grains were removed mainly by the photo-thermal effects introduced by excimer laser. The diamond structures ofthe protruded diamond grains were transfbrmed by the laser photonic energy into graphite, amorphous diamond and amorphous carbon which were remoyed by the subsequent laser shots. Laser ablation could improve the surface rouglmess from above 1pm to around O.1pm in few minutes' time in this study, However scanning would be required to coyer a large area, and, as a consequence, it could be very time consuming. Thermo-chemical polishing, in the other hand, was proved to be able to remove the diamond film very effectively (4.8pm deep of diamond film was removed in 30 minutes when polishing at 5500C and 5.7mfs) and the removal rate increased with pQlishing speed, temperature and pressure. Gases such as 02, 02 1 CF4, 021 SF6 were used as the reactive gases in the RIE experiments and it was fbund that 02 and 021SF6 offered better results. Howeyer, the obtained eteh rates were higher at areas like grain boundary and sharp corners which made further improvement ofsurface rouglmess very difficult.

An improved silicon-on-insulator (SOI) MOSFET transistor structure is presented. The structure. retains the density and lowcapacitance advantages of SOI, but places the transistor channel region in the single-crystal silicon substrate. This "seeded-channel" configuration avoids floating-body effects and ensures that defects in the SO1 will not affect the channel mobility. The technology has been used to successfully fabricate n-channel transistors.

A 3.1‐inch flexible active matrix OTFT‐OLED display had been demonstrated on the plastic substrate with process temperature below 200°C. To realize the flexible AMOLED, we replace ITO by Ag and develop surface control method to achieve high uniformity OTFT array and the lifetime of half Id is over 5000hrs.

The reduction of photo-leakage current of amorphous silicon thin-film transistors (a-Si TFTs) is investigated and is found to be successfully suppressed by the use of an n-doped nanocrystalline silicon layer (n+ nc-Si) as an ohmic contact layer. The shallow-level defects of n+ nc-Si can become trapping centres of photo-induced electrons as the a-Si TFT is operated under light illumination. A lower oxygen concentration during n+ nc-Si deposition can increase the creation of shallow-level defects and improve the contrast ratio of active matrix organic light-emitting diode panels.