High quality SiO 2 gate insulators are one of the key technologies for improving performance of Low Temperature Poly Silicon TFTs. We have developed an ALD/PECVD reactor, which handles 370 mm 470 mm glass substrates. The reactor has a unique plasma source of the monopole antenna, which is the electromagnetic wave coupled type and operates at VHF range. A PE-ALD SiO 2 film was deposited at 200 with alternating exposures of aminosilane and radical oxygen generated by the plasma. Growth rate of the film and thickness variation were 0.1 nm cycle -1 and less than 5 %, respectively. Conformal film growth was observed on patterned substrates. Uniform current-voltage performance was confirmed on the glass and its electrical field was higher than 8.0 MVcm -1 at a leakage current of 1×10 -6 Acm -2 . The film had an excellent Si / SiO 2 interface trap density of lower than 1×10 11 cm -2 eV -1 after forming gas annealing.

The optical phenomena occurring during the initiation of breakdown in the trigatron spark gap in air have been investigated with voltages up to 1 MV and inter-electrode spacings up to 60 cm, using an image converter as an electro-optical shutter. Measurements of gap current flowing during the breakdown initiation process have also been made. The optical phenomena are similar in nature to those occurring in long untriggered gaps. One or more leader strokes occur, followed by a main stroke. Leader stroke velocities fall within the range 5 x IO6 to 3.2 X lo8 cm sec-', depending on experimental conditions. The average mainstroke velocity is about 10' to IO9 cm sec-'. Under certain conditions the path taken by the complete spark is partly governed by the production of a short leader stroke originating at one electrode. It is shown that this leader occurs only in the region of the gap where conditions laid down by Loeb and Meek and Raether as being suitable for streamer formation and propagation are satisfied.

Zinc oxide (ZnO) thin films have attracted significant attention for application in thin film transistors (TFTs) due to their specific characteristics, such as high mobility and transparency. In this paper, the authors fabricated TFTs with ZnO thin films as channel layers deposited by plasma-assisted atomic layer deposition (PAALD) at 100 °C using two different plasma sources, water (H2O-plasma) and oxygen gas (O2-plasma), as oxidants, and investigated the effects of the plasma sources on TFT performances. The TFT with ZnO channel layer deposited with H2O-plasma indicated higher performances such as a field effect mobility (μ) of 1.1 cm2/Vs. Analysis of the ZnO films revealed that the residual carbon in the film deposited with H2O-plasma was lower than that of O2-plasma. In addition, the c-axis preferred orientation was obtained in the case of the ZnO film deposited with H2O-plasma. These results suggest that it is possible to fabricate high-performance ZnO TFTs at low temperatures by PAALD with H2O-plasma.

In this study, we deposited zinc oxide (ZnO) thin films by atomic layer deposition (ALD) as an active channel layer in thin film transistor (TFT) using two different oxidizers, water (H 2 O-ALD) and oxygen radical (PA-ALD). The fabricated TFTs were annealed at various temperatures, in oxygen ambient gas. The electrical properties of TFTs with PA-ALD ZnO film annealed at the temperature up to 400 o C improved without any degradation of the subthreshold swing or any large shift of the threshold voltage. Through this study, we found that the high performance ZnO TFTs is possible to obtain by using PA-ALD at low temperature, and the electrical properties are dependent on the annealing temperature.

No abstract